The key terms associated with determining your application inventory are:

1.Determination

2.Collection

3.Supply

4.Analysis and resolution of exceptions

32.4.2.1 Determination

Determination is the task of understanding what runs in production on the VSE side. It includes finding out all the places where the production JCL is stored and determining what is production and what is not production.

32.4.2.2 Collection

Collection is about building a procedure using standard utilities or ad hoc programs to transfer all the source (JCL, source programs and copy books) to the OS/390 side.

32.4.2.3 Supply

Supply is the procedure where you transfer the source code and JCL, from the source environment, VSE or VM, to the OS/390 system. The determination, collection and supply happen on the VSE side.

Only the version of source code or JCL currently used in production under VSE is supplied to the conversion. Duplicate or obsolete versions are eliminated (moved away) from the VSE production libraries. VSE executable code (phases) is discarded: new OS/390 executable code (load-modules) will be generated from the converted source code. Lost source code is either retrieved or rewritten: it is then regression tested and installed in production under VSE before being transferred to the OS/390 system for conversion.

The device, content, and format of the files used to transfer the conversion inventory from the VSE to the OS/390 system are defined. An automated application transfer procedure (VSE JCL streams and OS/390 JCL streams) is developed. The conversion inventory is collected from the VSE production libraries, copied to transfer files and downloaded into the conversion libraries on the OS/390 system.

In the mass method the supply is renewed each month. This helps synchronize both sides by keeping the VSE portion more current and ensuring the MVS side has access to a recent VSE copy.

32.4.2.4 Analysis and Resolution of Exceptions

This is also known as Inventory Validation. It involves analyzing the relationships in the inventory and uncovering and resolving exceptions. Validation is the process of determining to what each element is linked, what those elements include and to follow the chain to see what is referenced, what is missing and what is unreferenced. Missing elements can be identified where a piece of JCL calls for program ABC but the source ABC is missing or the piece of JCL is not production JCL. The same is true with unreferenced elements. When you have unreferenced elements there are two causes. It could be an obsolete item or the piece of JCL that referred to it is missing.

The end result of resolving these exceptions is a clean and accurate inventory.

In the Cortex environment this is arrived at through the running of validation tools against the conversion libraries on the OS/390 side. Validation could also

496VSE to OS/390 Migration Workbook

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IBM OS/390 manual Determination, Collection, Supply, Analysis and Resolution of Exceptions

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.