18.5.1 REXX and SAA

Issuing commands to the surrounding environment is an integral part of REXX. REXX is the only procedure language supported by the SAA to help provide cross-system consistency. Procedures written in REXX according to the SAA specifications can be transported to other SAA environments. For example, a REXX exec in CMS can also run in a TSO/E environment if the exec does not use system-specific functions or commands.

Only the ADDRESS command/instruction affects the host command environment of the exec that uses the command/instruction.

18.6 REXX Bibliography

VSE/ESA

VSE/REXX Reference, SC33-6642

VSE/REXX Users Guide, SC33-6641

VSE/REXX Console Automation, SC33-6598

VM/ESA

VM/ESA REXX/VM Users Guide, SC24-5465

VM/ESA REXX/VM Reference, SC24-5770

TSO/E

OS/390 V1R2.0 TSO/E REXX Reference, ST01-2613

OS/390 OPENEDITION MVS using REXX and OPENEDITION MVS, ST01-2695

372VSE to OS/390 Migration Workbook

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IBM OS/390 manual Rexx and SAA, Rexx Bibliography

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.