Ion Of Db2 With Vsam

DB2 DB2 is an abbreviation for IBM Database 2 and was launched in June 1983 as a subsystem on MVS that allowed MVS users to build, access, and maintain relational databases using the well known Structured Query language (SQL). Since then, DB2 has come a long way and provides facilities to exploit the latest hardware and software technologies, accommodating a majority of user requirements. The latest versions are available on almost all platforms, including Windows, HP-UX, Sun Solaris, Unix, AIX, NUMAQ, Linux, AS/400 and OS/390. As the name suggests, DB2 "Universal Database" provides universal data types, universal integration, universal access from clients of all types, universal applicability (for all types of applications), universal scalability (across all types of platforms), universal reliability (for non-stop 24/7 processing) and universal manageability. The ability to manage many concurrent users, very large databases, high transaction rates and deliver consistent rapid response is fundamental and delivered by DB2 through the wide range of platforms and the exploitation of platform-specific features. Beyond this, DB2 meets the requirements for high availability, low planned maintenance, wide connectivity, open standards and effective manageability. VSAM VSAM is a high-performance access method used in the MVS, OS/390 and VSE/ESA operating systems. It was initially released by IBM in 1973 and is part of the Base product. VSAM provides a number of data set types or data organization schemes. They are: • • • • •

Key-sequenced data set (KSDS) Entry-sequenced data set (ESDS) Relative record data set (RRDS) Variable-length relative record data set (VRRDS) Linear data set (LDS)

Installations have been using VSAM data sets to hold more and more of their data to the point where many have reached the 4-gigabyte architectural limit for the size of VSAM data sets. Beginning with DFSMS V1.3, you can create and use VSAM KSDSs that can be much larger than the 4-gigabyte limit imposed on any VSAM data set defined before this release. DFSMS V1.5 allows non-KSDS file types (ESDS, RRDS, VRRDS and LDS) to exceed 4 gigabytes. VSAM record-level sharing (RLS) was introduced to provide the value of the Parallel Sysplex to the existing applications. RLS itself does not provide transactional recovery. CICS provides a file access interface on top of VSAM. It is a CICS file control function

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that includes transactional recovery for VSAM files. This isolation and rollback capability enables VSAM data to be shared among CICS applications. Comparison of DB2 and VSAM Feature Hardware Independence OS Independence Vendor Independence Scalability

Ease development Ease maintenence Security Referential Integrity

DB2 PC to mainframe

VSAM Only Mainframe

NT, Unix & OS/390

Only OS/390

RBDMS with ANSI std.

Only IBM

PC to mainframes

Only Mainframe

Upto 4000 terabytes for Maximum size is 128 LOB terabytes of Standard SQL Not so simple Stored procedure triggers of Standard SQL

Query Interface Products/tool suite Data Capacity

& No such option Difficult

High degrees of security Only at Dataset level DB2 enforces it Developers responsibility Manages even externally stored data Not applicable Easy to view/modify Not available IBM & 3rd Parties

Not available

254 times largest VSAM

Limited to 2 terabytes Data sharing Across CICS, IMS, Batch, Very limited support TSO Web & Java JDBC, SQLJ, Net.data Need custom support interfaces Distributed Consistent across Only Mainframe environment platforms Not applicable Stored procs reduce network traffic XML support XML extenders Not supported Performance For less data Better when data is

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Feature

DB2

VSAM less

Better for large data For less data Optimizer handles Developer Partitioning performance Performance Tuning

improvesresponsible

Can be tuned anytime

No partitioning Depends on initial design

Writes SMF records No SMF records Can be at SQL level Only application level Tools available for aiding No tuning aids Subsystem possible CPU & parallelism Parallel Sysplex

level

tuning

Abundant tuning skills IO Scanning is Faster Can participate

Not a subsystem Tuning skills are rare No parallelism Can participate

Optimizer handles Reorganization Direct reorganization

No optimization Delete & recreate

Online reorg possible

Downtime needed

Parallel reorg Managed by DB2

No parallelism Managed by CICS/IMS

Always recoverable

No recovery in batch

From log / backup

From backup only

Auto Recovery

Manual Restore

Parallel recovery Online backup possible

No parallelism Downtime needed

Recovery

Backup

Incremental backup

No backup

incremental

Parallel backup

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Feature

Availability

DB2

Parallel reorg, backup

VSAM No parallelism No online maintenance

Online reorg, backup No parallelism Less downtime Disaster Recovery Data Archival

Personnel

Selective archival

More Downtime Part of DASD recovery No Selective archival

Selective retrieval

No Selective retrieval

Upto row level archival

Dataset level archival

Specific Products IBM & 3rd party training

Dataset Migration Not much training

Easy to find Skills

Scarce skill

Reuse any RDBMS skill

VSAM Specific skill

Supported by DB2

Same across platforms Data Warehouse

Real time updates Direct Propagation

Mainframe Specific skill Batch updates only Extract & transform

Product suites available Data types

Not suitable warehouse Images, Video, Audio etc Text only Contents can be in file

for

No such option

MVS MVS (Multiple Virtual Storage) is an operating system from IBM that continues to run on many of IBM's mainframe and large server computers. MVS has been said to be the operating system that keeps the world going and the same could be said of its successor systems, OS/390 and z/OS. The payroll, accounts receivable, transaction processing, database management, and other programs critical to the world's largest businesses are usually run on an MVS or successor system. Although MVS has often been seen as a

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monolithic, centrally-controlled information system, IBM has in recent years repositioned it (and successor systems) as a "large server" in a network-oriented distributed environment, using a 3-tier application model. The follow-on version of MVS, OS/390, no longer included the "MVS" in its name. Since MVS represents a certain epoch and culture in the history of computing and since many older MVS systems still operate, the term "MVS" will probably continue to be used for some time. Since OS/390 also comes with Unix user and programming interfaces built in, it can be used as both an MVS system and a UNIX system at the same time. A more recent evolution of MVS is z/OS, an operating system for IBM's zSeries mainframes. MVS systems run older applications developed using COBOL and, for transaction programs, CICS. Older application programs written in PL/I and FORTRAN are still running. Older applications use the Virtual Storage Access Method access method for file management and Virtual Telecommunications Access Method for telecommunication with users. The most common program environment today uses the C and C++ languages. DB2 is IBM's primary relational database management system (RDBMS). Java applications can be developed and run under OS/390's UNIX environment. MVS is a generic name for specific products that included MVS/SP (MVS/System Product), MVS/XA (MVS/Extended Architecture), and MVS/ESA (MVS/Enterprise Systems Architecture). Historically, MVS evolved from OS/360, the operating system for the System/360, which was released in 1964. It later became the OS/370 and the System/370. OS/370 evolved into the OS/VS, OS/MFT, OS/MVT, OS/MVS, MVS/SP, MVS/XA, MVS/ESA, and finally OS/390 and then z/OS. Throughout this evolution, application programs written for any operating system have always been able to run in any of the later operating systems. (This is called forward compatibility.) An MVS system is a set of basic products and a set of optional products. This allows a customer to choose the set of functions they need and exclude the rest. In practice, most customers probably use almost all of the functions. The main user interface in MVS systems is TSO (Time Sharing Option). The Interactive System Productivity Facility (ISPF) is a set of menus for compiling and managing programs and for configuring the system. The main work management system is either Job Entry Subsystem 2 or 3 (JES2 or JES3). Storage (DASD) management is performed by DFSMS (Distributed File Storage Management Subsystem). MVS is considerably more complex and requires much more education and experience to operate than smaller server and personal computer operating systems. The Virtual Storage in MVS refers to the use of virtual memory in the operating system. Virtual storage or memory allows a program to have access to the maximum amount of memory in a system even though this memory is actually being shared among more than one application program. The operating system translates the program's virtual address into the real physical memory address where the data is actually located. The Multiple in MVS indicates that a separate virtual memory is maintained for each of multiple task partitions.

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Other IBM operating systems for their larger computers include or have included: the Transaction Processing Facility (TPF), used in some major airline reservation systems, and VM, an operating system designed to serve many interactive users at the same time MAINFRAME UTILITIES IBM mainframe utility programs are supplied with IBM mainframe operating systems such as MVS to carry out various tasks associated with datasets, etc.

Disk drive support ICKDSF ICKDSF ("Device Support Facility") installs, initializes and maintains DASD, either under an operating system, or standalone.

VSAM utilities IDCAMS IDCAMS ("Access Method Services") generates and modifies VSAM and Non-VSAM datasets. The "Access Method" reference derives from the initial "VSAM replaces all other access methods" mindset of OS/VS. It probably has the most functionality of all the utility programs, preforming many functions, for both VSAM and non-VSAM files. It was intended to replace most of the other dataset utility programs.

Dataset utilities IEBCOMPR IEBCOMPR compares records in sequential or partitioned datasets. The IEBCOMPR utility is used to compare two sequential or partitioned data sets. This data set comparison is performed at the logical record level. Therefore, IEBCOMPR is commonly used to verify that a backup copying of a data set is current. During processing, IEBCOMPR compares each record from each data set, one by one. If the records are unequal, IEBCOMPR lists the following information in the SYSOUT: - The record and block numbers in question. - The names of the DD statements in which the inconsistency occurred. - The unequal records.

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When comparing sequential data sets, IEBCOMPR considers the data sets equal if the following conditions are met: - The data sets contain the same number of records. - The corresponding records and keys are identical. For partitioned data sets, IEBCOMPR considers the data sets equal if the following conditions are met: - The directory entries for the two partitioned data sets match - that is, the names are the same, and the number of entries are equal. - The corresponding members contain the same number of records. - The corresponding records and keys are identical. If ten unequal comparisons are encountered during processing, IECOMPR terminates with the appropriate message. //XXXXXXXW JOB //S010IEBC EXEC // INCLUDE //SYSIN DD //* //SYSUT1 DD //SYSUT2 DD //SYSUT# DD

XXXXXXX,AAAA.A.A,CLASS=G,MSGCLASS=1,NOTIFY=XXXXXXX PGM=IEBCOMPR,ACCT=PJ00000000 MEMBER=@BATCHS DUMMY UNIT=DASD,DISP=SHR,DSN=XXXXXXX.PREVBIB UNIT=DASD,DISP=SHR,DSN=XXXXXXX.PREVCAT

IEBCOPY IEBCOPY copies, compresses and merges partitioned datasets. It can also select or exclude specified members during the copy operation, and rename or replace members. Some of the tasks that IEBCOPY can perform include the following: - Creating a backup of a PDS - Copying a PDS in place to reclaim the unused space from deleted members; Also called compressing a PDS. - Copying selected members to another PDS. - Renaming selected members of a PDS. - Merging multiple partitioned data sets into a single PDS. - Altering, copying and reblocking load moduled. 7

The IEBCOPY utility differs from the other IEB-type utilities in that the DDNAMEs of the input and output DD statements are defined by the JCL code as opposed to using the standard SYSUT1 and SYSUT2 DDNAMEs. For the IEBCOPY utility, the required job control statements are as follows: //stepname //SYSPRINT //anyname1 //anyname2 //SYSUT3 //SYSUT4 //SYSIN

EXEC PGM=IEBCOPY DD SYSOUT=class DD ... DD ... DD ... DD ... DD ...

The EXEC statement specifies the utility program name IEBCOPY. You can give this EXEC statement any stepname you wish, as long as you adhere to the naming conventions for JCL statements. Following the EXEC statement are the specific DD statements used by IEBCOPY. These DD statements must appear in every step that uses IEBCOPY. In addition, the DD statements can be listed in any order within the step. The SYSPRINT DD statement specifies a message data set to which the output message generated from the utility, such as error and allocation messages, are sent. The anyname1 and anyname2 DD statements are specific to the IEBCOPY utility. These DD statements indicate the partitioned input and output data sets, respectively. You can use any DDNAME for these two DD statements, as long as you adhere to the naming conventions for DDNAMEs. As you will see, these DDNAMEs are specified in the utility control statements to tell IEBCOPY the name of the input and output data sets. The SYSUT3 statement specifies a spill (work) data set on DASD that is used to hold the input data set's directory entries during the copying. This work data set is used if there is not enough virtual storage allocated to the program by the JOB or EXEC statement REGION parameter. The SYSUT4 DD statement also specifies a spill(work) data set on DASD. This is used to hold the output data set's directory entries during the copying, if enough virtual storage is not available. The SYSIN DD statement specifies the utility control data set.

IEBDG IEBDG ('Data Generator') creates test datasets consisting of patterned data.

IEBEDIT IEBEDIT selectively copies portions of JCL. An example of an IEBEDIT program: //IEBEDITJ JOB ACCT,'',CLASS=P,MSGCLASS=T,MSGLEVEL=(1,1),NOTIFY=&SYSUID

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//STEP0001 EXEC PGM=IEBEDIT //SYSPRINT DD SYSOUT=* //SYSUT1 DD DSN=xxxxx.yyyyy.zzzzz,DISP=SHR //SYSUT2 DD SYSOUT=(*,INTRDR) //SYSIN DD * EDIT TYPE=INCLUDE,STEPNAME=(STEP10,STEP5,STEP15) /* //

In data set xxxxx.yyyyy.zzzzz you have to write a JCL program which contains 15 steps. After that you have to execute the above program.

IEBGENER IEBGENER copies records from a sequential dataset, or creates a partitioned dataset. Some of the tasks that IEBGENER can perform include the following: - Creating a backup of a sequential data set or a member of a PDS. - Changing the physical block size or logical record length of a sequential data set. - Creating an edited data set. - Printing a sequential data set or a member of a PDS. - Creating partitioned output data set from sequential input data set. An example of an IEBGENER program to copy one dataset to another: //IEBGENER //STEP010 //SYSUT1 //SYSUT2 // // //SYSPRINT //SYSIN

JOB ACCT,'DATA COPY',MSGCLASS=J,CLASS=A EXEC PGM=IEBGENER DD DSN=xxxxx.yyyyy.zzzzz,DISP=SHR DD DSN=aaaaa.bbbbb.ccccc,DISP=(,CATLG), DCB=(RECFM=FB,LRECL=1440),SPACE=(TRK,(5,5),RLSE), UNIT=SYSDA DD SYSOUT=* DD DUMMY

The EXEC statement specifies the program IEBGENER. You can give this EXEC statement any stepname that you wish, as long as you adhere to the naming conventions for JCL statements. Following the EXEC statement, ate the specific DD statements used by IEBGENER. These DD statements must appear in every step that uses IEBGENER. In addition, the DD statements can be listed in any order within the IEBGENER step. The SYSPRINT DD statement specifies a message data set to which the output message generated from the utility, such as information and error message, are sent. Remember that the SYSPRINT DD statement can specify a system output device, a tape data set, or a DASD data set.

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The SYSUT1 DD statement specifies the input data set, that is, the name of the data set that you wish to copy. For the the IEBGENER utility, this DD statement specifies a sequential data set or a member of a PDS. The SYSUT2 DD statement specifies the output data set, that is, the name of the data set you wish to create or to which you wish to copy members. This DD statement specifies a sequential data set, a PDS, or a member of a PDS. The SYSIN DD statement specifies the utiity control statements. The utility control statements are optional for IEBGENER. If utility control statement are used, the SYSIN DD statement defines instream data, a sequential data set, or member of a PDS. If you do not need to include any utility control statement you should specify a DUMMY parameter on the SYSIN DD statement. On some systems it is possible to send email from a batch job by directing the output to the "SMTP" external writer. On such systems, the technique is as follows: //IEBGENER JOB ACCT,'DATA COPY',MSGCLASS=J,CLASS=A //NORMRC EXEC PGM=IEBGENER //SYSPRINT DD SYSOUT=* //SYSUT1 DD *,LRECL=80 HELO <SYSTEMID> MAIL FROM: RCPT TO: DATA From: To: Subject: Test Mail TEST MAIL FROM MAINFRAME . QUIT /* //SYSUT2 DD SYSOUT= (B, SMTP), LRECL=80 //SYSIN DD DUMMY

IEBIMAGE IEBIMAGE manipulates character set definitions (aka "load modules" or "images") for the IBM 3800 printing subsystem.

IEBISAM IEBISAM unloads, loads, copies and prints ISAM datasets. (OBSOLETE) ISAM is no longer supported by most modern operating systems. VSAM is used instead. See IDCAMS.

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IEBPTPCH IEBPTPCH ("PrinT and PunCH") prints or punches records from a sequential or partitioned dataset. Some of the tasks that IEBPTPCH can perform include the following: - Printing or punching an entire data set, sequential or partitioned (PDS). - Printing or punching selected PDS members. - Printing or punching selected records from a sequential or partitioned data set. - Printing or punching a PDS directory. - Printing or punching an edited version of a sequential data set or PDS. //IEBPTPCH // //SYSIN PRINT TITLE TITLE RECORD

JOB EXEC PGM=IEBPTPCH DD * MAXFLDS=2 ITEM=('Name',22), ITEM=('GPA',50) ITEM=(' ',1) FIELD=(25,1,,22), FIELD=(4,51,,50)

/* //SYSPRINT DD SYSOUT=* //SYSUT1 DD * Person 1 Second person 3rd person /* //SYSUT2 DD SYSOUT=* //

307 C Meshel Hall 123 Williamson Hall 321 Maag Library

3.89 2.48 1.52

IEBUPDTE IEBUPDTE ("UPDaTE") incorporates changes to sequential or partitioned datasets. The UNIX "patch" utility is a similar program, but uses different input format markers (e..g, "./ INSERT ..." in MVS becomes "@@..." in Unix Patch). Some programmers pronounce it "I.E.B. up-ditty". The IEBUPDTE utililty is a utility used to maintain source libraries. Some of the functions that IEBUPDTE can perform include the following: - Creating and updating libraries

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- Modifying sequential data sets or PDS members - Changing the organization of a data set from sequential to partitioned or from partitioned to sequential. IEBUPDTE is commonly used to distribute source libraries from tape to DASD. IEBUPDTE uses the same job control statements required by most IEB-type utilities. The only exceptions are as follow: - IEBUPDTE accepts a PARM parameter coded on the EXEC statement. - IEBUPDTE reads the input data set from either the SYSUT1 DD statement or from the SYSIN DD statement. The job control used by IEUPDTE are as follows: //stepname //SYSPRINT //SYSUT1 //SYSUT2 //SYSIN

EXEC PGM=IEUPDTE,PARM=parm DD SYSOUT=class DD ... DD ... DD ...

The EXEC statement specifies the program IEBUPDTE and an optional PARM value, NEW or MOD. A PARM value of NEW indicates that the utility control statements and the input data are contained in the SYSIN DD statement. In this case, no SYSIN1 DD statement is required. A PARM value of MOD indicates that the SYSIN DD statement contains only utility control statements, as opposed to utility control statements plus the input data. Therefore, the SYSUT1 DD statement is required to define the input data set.

Scheduler utilities IEFBR14 IEFBR14 is a dummy program, normally inserted to JCL when the only desired action is allocation or deletion of datasets. An example of an IEFBR14 program: //IEFBR14 // //DELDD //

JOB ACCT,'DELETE DATASET' EXEC PGM=IEFBR14 DD DSN=xxxxx.yyyyy.zzzzz, DISP=(MOD,DELETE,DELETE),UNIT=DASD

It consisted initially as a single instruction a "Branch to Register" 14. The mnemonic used in the IBM Assembler was BR and hence the name: IEF BR 14.

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The calling sequence for OS/360 contained the return address in Register 14. A branch to Register 14 would thus immediately exit the program. However, before and after executing this program, the operating system would allocate & deallocate datasets as specified in the DD statements, so it is commonly used as a quick way to set up or remove datasets. This single instruction program had an error in it. It didn't set the return code and hence a second instruction had to be added to clear the return code so that it would exit with the correct status.

System utilities IEHINITT IEHINITT ("INITalize Tape") initializes tapes by writing tape labels. Multiple tapes may be labeled in one run of the utility. IBM standard or ASCII labels may be written. An example of an IEHINITT program: //IEHINITT JOB ACCT,'LABEL TAPES',MSGCLASS=J,CLASS=A //STEP0001 EXEC PGM=IEHINITT,REGION=8M //SYSPRINT DD SYSOUT=A //LABEL DD DCB=DEN=2,UNIT=(3490,1,DEFER) //SYSIN DD * LABEL INITT SER=123450,NUMBTAPE=3 /

This example will label 3 tapes on a 3490 magnetic tape unit. Each tape will receive an IBM standard label. The VOLSER will be incremented by one for each tape labeled. Each tape will be rewound and unloaded after being labeled.

IEHLIST IEHLIST is a utility used to list entries in a Partitioned Dataset (PDS) directory or to list the contents of a Volume Table of Contents (VTOC). The IEHLIST utility is used to list the entries contained in any one of the following: - PDS directory - VTOC - Catalog (OS CVOL) An example of an IEHLIST program: //IEHLIST JOB ACCT,'LIST PDS',MSGCLASS=J,CLASS=A //STEP0001 EXEC PGM=IHLIST,REGION=8M

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//SYSPRINT DD SYSOUT=A //PDS1 DD DSN=xxxx.yyyy.zzzz,DISP=OLD //SYSIN DD * LISTPDS DSNAME=xxxx.yyyy.zzzz,FORMAT /*

This job will produce a formatted listing of the PDS directory of the PDS named xxxx.yyyy.zzzz. An example of an IEHLIST program to list a VTOC is very similar: //IEHLIST JOB ACCT,'LIST VTOC',MSGCLASS=J,CLASS=A //STEP0001 EXEC PGM=IHLIST,REGION=8M //SYSPRINT DD SYSOUT=A //VOL1 DD VOL=SER=vvvvvv,DISP=OLD //SYSIN DD * LISTVTOC VOL=vvvvvv,FORMAT /*

IEHMOVE IEHMOVE moves or copies collections of data. (However, IBM does not recommend using the IEHMOVE utility in an SMS environment.) A move differs from a copy in that during a move the original data set is deleted, or scratched. Some of the tasks that IEHMOVE can perform include the following: - Moving or copying sequential and partitional data sets - Moving or copying multi- volume data sets - Moving an entire volume of data sets On the surface, IEHMOVE may seen redundant to the IEBGENER and IECOPY utilities. However, IEHMOVE is more powerful. The main advantage of using IEHMOVE is that you do not need to specify space or DCB information for the new data sets. This is because IEHMOVE allocates this information based on the existing data sets. Another advantage of IEHMOVE is that you can copy or move groups of data sets as well as entire volumes of data. Because of the ease in moving groups of data sets or volumes, the IEHMOVE utility is generally favored by system programmers. The job control statements required by the IEHMOVE utility are as follows: //stepname //SYSPRINT //SYSUT1 //anyname1 //anyname2

EXEC PGM=IEHMOVE,PARM='LINECNT=xx,POWER=n' DD SYSOUT=class DD UNIT=aaaa,VOL=SER=bbbbbb,DISP=OLD DD UNIT=cccc,VOL=SER=dddddd,DISP=OLD DD UNIT=eeee,VOL=SER=ffffff,DISP=OLD

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//SYSIN

DD

...

Following the EXEC statement are the specific DD statements used by IEHMOVE. These statements must appear in every step that uses IEHMOVE. In addition, DD statements used by IEHMOVE can be listed in any order within the job step. The DD statements for IEHMOVE, order than SYSPRINT and SYSIN, refer to DASD or tape volumes instead of individual data sets. However, referencing volumes can pose a problem. Remember that when you modify a data set, you allocate it with a disposition of OLD (DISP=OLD) to prevent other users from accessing the data set at the same time. However, specifying DISP= OLD grants exclusive access to a volume. Therefore, when your IEHMOVE job runs, other users cannot use the volumes allocated by IEHMOVE. This is acceptable for private volumes, such as tape volumes or mountable volumes, but unacceptable public volumes, such as DASD volumes. The SYSPRINT DD statement specifies a message data set to which the output message generated from the utility, such as information and error messages, are sent. The SYSUT1 DD statement specifies a DASD volume where three work data set required by IEHMOVE are allocated. You must specify unit and volume information for this DD statement. IEHMOVE was one of the first systems to be developed in PL/S.

IEHPROGM IEHPROGM builds and maintains system control data. It is also used for renaming and scratching (deleting) a data set. Some of the tasks that IEHPROGM can perform include the following: - Deleting (scratching) a data set or PDS member - Renaming a data set or PDS member - Cataloging or uncataloging a data set - Maintaining data set passwords

Supporting Programs (The following programs are not technically utilities -- they are not supplied with the Operating System, but are sold as separate packages. Still, as they are standard items required for programming the computer, nearly all shops will have them installed.)

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SORT The Sort/Merge utility is program to sort records in a file into a specified order, or merge pre-sorted files. It is very frequently used; often the most commonly used application program in a mainframe shop. Modern sort/merge programs also can select or omit certain records, summarize records, remove duplicates, reformat records, and produce simple reports. Sort/merge is important enough that there are multiple companies each selling their own sort/merge package for IBM mainframes.

IEWL IEWL (also known as HEWL) is the linkage editor used to create an executable load module from an object module. The linkage editor must be used to make an executable copy ('load module') of a compiled or assembled program produced by an assembler or compiler for some programming language. External symbols in the object module(s), optional linkage editor control statements, and linkage editor JCL parameters determine how the finished load module is to be constructed.

IGYCRCTL IGYCRCTL is a COBOL compiler that prepares a COBOL source program for execution by producing a machine-language object module. Note that the object module produced by the compiler must be processed by the linkage editor, IEWL, before the compiled program is ready for execution. (This is the compiler for the current IBM Enterprise COBOL for z/OS product; there have been several previous IBM COBOL compilers over the years, with different names, as well as compilers for various other programming languages.)

DFSMS DFSMS (System Managed Storage) is a set of programs that allows the operating system itself to take over many of the tasks of managing storage, tasks that were previously performed manually by systems programmers. The storage administrator defines classes of storage, and rules defining dataset assignment into these classes. From then on, the system manages the datasets automatically, taking care of assigning datasets to storage volumes, providing backup and recovery, migrating datasets up or down between secondary and tertiary storage as needed, and balancing usage of system resources. See also: hierarchical storage management.

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