2.7.5Project Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.7.6Automated Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.8Cost Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2.9OS/390 Documentation Resources . . . . . . . . . . . . . . . . . . . . . . . 39

2.9.1Introduction References . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.9.2 Key Documents and Other References . . . . . . . . . . . . . . . . . . 40

2.9.3Web URL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Chapter 3. Developing the Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.1Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.1.1References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.1.2Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.2Plan Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.1Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.2Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.3Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.2.4Milestone Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

3.2.5Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

3.3 Progressive versus Mass Conversion . . . . . . . . . . . . . . . . . . . . . . 49

3.3.1Approach Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

3.3.2Historical Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

3.3.3 Shared Application Files and Databases . . . . . . . . . . . . . . . . . 50

3.3.4Shared Application Code . . . . . . . . . . . . . . . . . . . . . . . . . . 50

3.3.5Operations Support Staffing . . . . . . . . . . . . . . . . . . . . . . . . . 50

3.3.6Automated Operations Tools . . . . . . . . . . . . . . . . . . . . . . . . 50

3.3.7 Standardized Conversion Deliverables and Automation . . . . . . . . 51

3.3.8Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.3.9Complexity of Implementation . . . . . . . . . . . . . . . . . . . . . . . 51

3.4Plan Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

3.4.1Project Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.4.2Project Plan Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Part 2. Converting the VSE Operating System to the OS/390 Operating System

. .

67

Chapter 4. Job Control Language (JCL) Differences and Considerations

. . .

69

4.1 The Philosophy of JCL in System/390

. . . .

69

4.1.1 VSE/ESAs Job Control Language Philosophy

. . . .

70

4.1.2OS/390s Job Control Philosophy . . . . . . . . . . . . . . . . . . . . . . 70

4.2High Level Similarities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

4.2.1JCL Statement and Job Layout . . . . . . . . . . . . . . . . . . . . . . . 72

4.2.2Spooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.3 JCL Differences Between VSE and MVS . . . . . . . . . . . . . . . . . . . . 73

4.3.1Job Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.3.2JCL Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

4.3.3 Operator Flexibility and Intervention . . . . . . . . . . . . . . . . . . . . 76

4.3.4Allocation of Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

4.3.5Hidden JCL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

4.3.6Device Address Specifications . . . . . . . . . . . . . . . . . . . . . . . 80

4.3.7Catalogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4.3.8Partition Dependent Codes in JCL . . . . . . . . . . . . . . . . . . . . . 81

4.3.9 Communication Region - DATE and UPSI . . . . . . . . . . . . . . . . . 81

4.3.10VSE Job Control Statements . . . . . . . . . . . . . . . . . . . . . . . . 82

4.3.11MVS Job Control Statements . . . . . . . . . . . . . . . . . . . . . . . 84

4.3.12 Comparison of VSE and MVS JCL - A Summary . . . . . . . . . . . . 86

ivVSE to OS/390 Migration Workbook

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IBM OS/390 manual Key Documents and Other References, Job Control Language JCL Differences and Considerations

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.