13.2.4.2 RELPAG Macro

The MVS PGRLSE and PGSER RELEASE macros have functions similar to the

VSE RELPAG macro.

￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

￿ VSE ￿ RELPAG ￿begin addr ,

end addr,777

￿

￿

￿

￿ (2-12)

(2-12)

￿

￿

￿

￿lis￿name

 

￿

￿

￿

￿ (1)

 

￿

￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

￿ MVS ￿ PGRLSE ￿ LA=addrl

,HA=addr2

￿

￿

￿

￿

(2-12)

(2-12)

￿

￿

￿

￿

(0)

(1)

￿

￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

When you issue the PGRLSE macro, all complete pages of virtual storage between the low and high addresses specified are released. You can help reduce system overhead by releasing virtual storage when you no longer need it.

Unlike VSE, you must issue a separate instruction for each area of storage you want to release.

13.2.4.3 PFIX and PFREE Macros

The MVS PGFIX and PGFREE macros correspond to VSE PFIX and PFREE. Use of the MVS instructions is restricted, however, to system functions and authorized users (key-0 and supervisor state). Further information about PFIX and PFREE appears in MVS SRL library publications.

13.2.4.4 SETPFA Macro

In MVS, only system functions and authorized users (key-0 and supervisor state) are permitted to handle their own page faults.

13.2.4.5 PAGEIN Macro

The MVS PGLOAD macro is similar to PAGEIN, but its use is restricted to system functions and authorized users (key-0 and supervisor state).

13.2.4.6 FCEPGOUT, RUNMODE, VIRTAD and REALAD Macros

These instructions have no equivalent in MVS.

13.2.5 VSAM Macros

Detailed information on the coding of MVS VSAM macros can be found in the publication DFSMS/MVS Macro Instructions For Data Sets, SC26-4913.

13.2.5.1 ACB Macro

The ACB macro is source-compatible except for the parameter ²P A R M S = ² which was introduced by VSE VSAM Release 2 to support VSE VSAM Space Managed files. MVS VSAM does not support this type of file. Programs using this VSE feature should be converted to use MVS Sequential Access Method (SAM), or VSAM ESDS files.

Additional MVS VSAM ACB Parameters

290VSE to OS/390 Migration Workbook

Page 314
Image 314
IBM OS/390 manual Vsam Macros

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.