Chapter 19. SORT

This chapter addresses considerations for migrating to the OS/390 Sort product, DFSORT (5740-SM1) from the VSE Sort products:

DOS/VS SORT/MERGE V2 (5746-SM2), referred to as Sort/Merge

DFSORT/VSE V3 (5746-SM3), referred to as DFSORT/VSE

DFSORT/VSE is based on and replaces Sort/Merge. It offers additional features not available with Sort/Merge. The migration considerations for Sort/Merge will be discussed first. These considerations also apply to DFSORT/VSE. Migration considerations for additional features of DFSORT/VSE are discussed separately at the end of the chapter.

The interfaces for calling DFSORT from a program and for DFSORT user exit routines are significantly different from the corresponding interfaces for Sort/Merge. Your calling programs and user exits thus require careful consideration and redesign, as appropriate. These interfaces are described fully in the DFSORT Application Programming Guide, SC33-4035 and will not be discussed here.

Sort/Merge, DFSORT/VSE and DFSORT were designed to be functionally compatible at the control statement level, and for the most part, the control statement syntax of the three products is compatible. However, differences in JCL, data set usage and control statement syntax must be addressed when migrating to DFSORT. These differences are summarized in this chapter.

DFSORT has many features that are not available with Sort/Merge and some features that are not available with DFSORT/VSE. These additional DFSORT features are only discussed here when they relate to migration considerations. However, you may want to familiarize yourself with these additional features since they can be useful for your DFSORT applications.

For complete details on DFSORT, see the DFSORT Application Programming Guide, SC33-4035.

The following topics are discussed:

19.1, JCL Statements

19.2, Control Statements

19.3, Additional DFSORT/VSE Migration Considerations

19.1 JCL Statements

As discussed in Chapter 4, ªJob Control Language (JCL) Differences and Considerationsº on page 69, the JCL for OS/390 is quite different from that for VSE. You will need to replace your VSE JCL statements with appropriate OS/390 JCL statements. Every DFSORT job requires a JOB statement and an EXEC statement. DFSORT jobs also require specific DD statements which depend on the type of application being run (sort, merge or copy) as well as specific features you want to use for the job.

A basic DFSORT job might look as follows:

© Copyright IBM Corp. 1998

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IBM OS/390 manual Sort, JCL Statements, 375

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.