Chapter 18. Procedure Language REXX
16.2 FORTRAN Conversion Considerations
Chapter 17. Language Environment (LE)

15.11.1Storage Management in DOS . . . . . . . . . . . . . . . . . . . . . 345

15.11.2Storage Management in MVS . . . . . . . . . . . . . . . . . . . . . 345

15.12PL/I and CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.1File Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.2Statements not Supported . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.3CALLing DUMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.4Execution Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.5Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346

15.12.6PL/I-CICS/VS Transaction ABEND Codes . . . . . . . . . . . . . . . 346

15.12.7 PL/I Return from ON-units and CICS Transaction Backout . . . .

347

Chapter 16. FORTRAN

349

16.1VS FORTRAN in OS/390 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349

. . . . . . . . . . . . . . . . . . . . 349

. . . . . . . . . . . . . . . . . . . . . 351

17.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

17.1.1General Comments on Language Environment . . . . . . . . . . . . 351

17.1.2Conceptual Differences between LE/VSE and OS/390 Language

Environment

. . . . . . . . . . . . . . . . . . .

352

17.2 VSE to OS/390 Migration Considerations

. . . . . . . . . . . . . . . . . .

352

17.2.1LE/VSE-conforming Languages . . . . . . . . . . . . . . . . . . . . . 352

17.2.2Useful Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353

17.3 Migrating from LE/VSE-Conforming Languages . . . . . . . . . . . . . . 353

17.3.1C for VSE/ESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353

17.3.2COBOL for VSE/ESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

17.3.3PL/I for VSE/ESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

17.4 Migrating from Non-LE/VSE Run-time Environments . . . . . . . . . . . 354

17.4.1Options Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

17.4.2C/370 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

17.4.3VS COBOL II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

17.4.4DOS/VS COBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

17.4.5DOS PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

17.4.6VS FORTRAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358

17.4.7Migrating Interlanguage Communications Applications . . . . . . . 358

17.4.8 Migrating Assembler Applications . . . . . . . . . . . . . . . . . . . 359

17.5Migrating from LE/VSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

17.5.1Run-time Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

17.5.2

User Exits and Abnormal Termination Exits

364

17.5.3

Callable Services and Math Services

. . . . . . . . . . . . . . . . .

365

17.5.4LE/VSE 1.4 Locales . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

17.6CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

17.6.1COBOL and CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

17.6.2Run-time Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

17.6.3 User Exits and Abnormal Termination Exits . . . . . . . . . . . . . . 367

. . . . . . . . . . . . . . . . . . . . . . 369

18.1REXX and VM/ESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369

18.2REXX and VSE/ESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369

18.3REXX and TSO/E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369

18.4Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370

18.4.1VSE/ESA Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 370

18.4.2VM/ESA Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 370

18.4.3TSO/E Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371

18.4.4 REXX Exec Sample for the OS/2, TSO and CMS Environments . . 371

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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.
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