Chapter 10. POWER and JES2

10.1 JES2 Introduction

VSE uses POWER as a spooling system. MVS uses either JES2 or JES3 as spooling systems. This chapter only addresses migrations from POWER to JES2.

While POWER and JES2 are similar in their overall function, they are very different in design and specific implementations. Because of these differences in processing spool output, you may have to redesign some of your output procedures when migrating to MVS.

No attempt is made here to discuss the many advanced functions available in JES2. You should learn them from JES2 education classes and the JES2 publication library. What will be addressed will be a comparison of POWER functions and their JES2 equivalents as appropriate.

The chapter is divided into four sections:

1.The first section introduces the major POWER and JES2 functional differences, including migration considerations.

2.The second section describes significant tasks required to implement JES2.

3.The third section compares the functions and capacity of POWER and JES2 in more detail.

4.The fourth section shows a detailed mapping of POWER parameters, exits and commands to their JES2 counterparts.

10.1.1Major Differences

There are some major POWER unique functions, which, if used, will have to be accomplished in some other way in MVS. The following lists these functions and possible MVS alternate suggestions.

10.1.1.1 KEEP Disposition for Pre-Execution Jobs

In POWER, the user can specify that an input job be kept. Thus after the job is executed, it still remains in the POWER spool, for submission over and over.

In JES2 there is no KEEP disposition for spooled input jobs, as there is for SYSOUT data sets. Possible solutions in MVS to accomplish retaining submitted jobs include:

Append a jobstep to the end of these jobs to resubmit themselves in TYPRUN=HOLD condition.

Use a standard automated job scheduling package, such as OPC/ESA.

With SDSF and ISPF, you can edit the jobs JCL and resubmit the job, as long as it has not been purged from the JES2 spool. (Keep some output around so it is not purged.)

© Copyright IBM Corp. 1998

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IBM OS/390 manual Power and JES2, 10.1 JES2 Introduction, Major Differences, Keep Disposition for Pre-Execution Jobs, 207

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.