4.5.2 Sample MVS JCL

The task surrounding the conversion of JCL is more than mapping between VSE JCL using this syntax and MVS JCL using that syntax. At the base of these two JCLs are different philosophies. A parameter by parameter comparison is insufficient. Comparing the VSE DLBL/EXTENT to a DD Statement is only part of the story. These examples are meant to give the read only a ²flavor² for what changes have to take place. It is necessary to look at the two systems at a higher level as well.

//MYJOB JOB ACCT#,′ REPORT BY PLANT′ , CLASS=F,REGION=4M //*

//STEP1 EXEC PGM=PROGRAM1 //SYSLST DD SYSOUT=W COPIES=3 //TAPEIN DD DSN=INPUT.TAPE,DISP=OLD, // UNIT=TAPE,VOL=SER=REEL22

//DISKOUT DD DSN=WORK.DISK,DISP=(,CATLG),

//UNIT=SYSDA,SPACE=(TRK,(500,100),RLSE)

//*

//STEP2 EXEC PGM=SORT,COND=(0,NE)

//SORTIN DD DSN=WORK.DISK,DISP=(OLD,DELETE) //SORTOUT DD DSN=WORK.DISK2,DISP=(,CATLG),

//UNIT=SYSDA,SPACE=(TRK,(500,100),RLSE) //SYSOUT DD SYSOUT=*

//SYSIN DD *

SORT FIELDS=(1,32,CH,A) RECORD TYPE=F,LENGTH=87 /*

//SORTWK01 DD UNIT=SYSDA,SPACE=(TRK,(500,100)) //SORTWK02 DD UNIT=SYSDA,SPACE=(TRK,(500,100)) //*

//STEP3 EXEC PGM=PROGRAM2,COND=(O,NE) //SYSLST DD SYSOUT=F,FCB=FK33

//DISKIN DD DSN=WORK.DISK2,DISP=(OLD,DELETE) //DEST01 DD SYSOUT=A,DEST=KCJONES //DEST02 DD SYSOUT=A,DEST=HERBERT

//SYSIN DD * 01 ENDICOTT

02 BOEBLINGEN

1.Conditional OPENs

An example of the higher level differences between OS/390 and VSE is in the area of allocation. In OS/390, allocation is at the beginning of the step. VSE does not open a file until an OPEN is issued. This is a key concept and one that requires more than a term by term comparison. Frequently in VSE there are applications that open a file for output once a week on Friday. On other days this VSE file won¢t be opened. In OS/390, a data set will be created every day whether it is used or not. These high level type differences must also be addressed and as early in the migration as possible.

2. In-stream DD Card

There are three or four techniques to handle these situations.

One method is to convert the imbedded in-stream DD CARD by having the

JCL Batch of DD Names that somehow tie up the control cards and have

PROGRAM2 call some subroutine that would change the DD Name.

Chapter 4. Job Control Language (JCL) Differences and Considerations 93

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IBM OS/390 manual Sample MVS JCL, Myjob JOB ACCT#,′ Report by PLANT′ , CLASS=F,REGION=4M, Sysin DD * 01 Endicott Boeblingen

OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.