Disk and Tape Storage Considerations | IBM OS/390 specification

4.3.13 Summary of MVS JCL Statements . . . . . . . . . . . . . . . . . . . . 88

4.4JECL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.4.2	Comparison of POWER and JES2 JECL - A Summary	. . . . . . . . .	89
4.4.3	Summary of JES2 JECL - A Table	. . . . . . . . . . .	90
4.5 VSE and MVS JCL Comparison Example		. . . . . . . . . . .	91

4.5.1Sample VSE JCL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.5.2Sample MVS JCL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.5.3Sample VSE plus Carry-Over . . . . . . . . . . . . . . . . . . . . . . . . 94

Chapter 5. Disk and Tape Storage Considerations	. . . . . . . . . . . . . . . .	97
5.1 Access Method Similarities and Differences	. . . . . . . . . . . . . . . . . .	97

5.1.1Access Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

5.1.2 Operating System Implementations . . . . . . . . . . . . . . . . . . . . 98

5.1.3Miscellaneous Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.2Data Set Naming Considerations . . . . . . . . . . . . . . . . . . . . . . . . 99

5.2.1VSE Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.2.2OS/390 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.3Storage and Space Management . . . . . . . . . . . . . . . . . . . . . . . 100

5.3.1VSE Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

5.3.2OS/390 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

5.3.3System Managed Storage . . . . . . . . . . . . . . . . . . . . . . . . . 100

5.3.4Implementing DFSMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

5.4Tape Similarities and Differences . . . . . . . . . . . . . . . . . . . . . . . 103

5.4.1Volume Interchangeability . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.4.2Standard Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.4.3No Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

5.4.4Nonstandard Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

5.4.5 Bypass Label Processing Facility in OS/390 . . . . . . . . . . . . . . 106

5.5DASD Similarities and Differences . . . . . . . . . . . . . . . . . . . . . . 108

5.5.1Volume Interchangeability . . . . . . . . . . . . . . . . . . . . . . . . . 108

5.5.2DASD (VTOC) Processing . . . . . . . . . . . . . . . . . . . . . . . . . 108

5.5.3 Indexed VTOC Considerations (OS/390) . . . . . . . . . . . . . . . . . 109

5.6VSAM Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.6.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.6.2OS/390 Catalogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.6.3OS/390 Catalog Management . . . . . . . . . . . . . . . . . . . . . . . 114

5.6.4 OS/390 - VSE/VSAM Catalog Compatibility . . . . . . . . . . . . . . . 117

5.6.5VSAM Functional Differences . . . . . . . . . . . . . . . . . . . . . . . 119

5.6.6Data Sharing and Integrity . . . . . . . . . . . . . . . . . . . . . . . . . 125

5.6.7	Programming Languages and VSAM Support	131
5.6.8	VSAM Error and Reason Code Compatibility	131
5.6.9	DFSORT and VSAM Considerations	131

Chapter 6. CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

6.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

6.1.1	Overview CICS Transaction Server		133
6.1.2	Essential Supplemental Reading and Migration Support Material .		134
6.1.3	General Compatibility Comments		135
6.1.4	Virtual Storage Considerations for MVS		135
6.1.5	CICS General System Considerations		136
6.1.6	CICS Macro Resource Definition Table Changes		140
6.1.7	CSD and RDO Considerations	. . . . . . . . . . . . . . . . . . . . . .	143
6.1.8	CICS System Data Sets Requirements		145
6.1.9	CICS System Program Interface and Exits		147
6.1.10	CICS Transaction Security		149

Contents v

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.

IBM OS/390 manual Disk and Tape Storage Considerations, Operating System Implementations

Models: OS/390

Chapter 5. Disk and Tape Storage Considerations

5.1.2 Operating System Implementations . . . . . . . . . . . . . . . . . . . . 98

OS/390 specifications