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At project start

Before the start of online application tests

Before the start of batch application tests

Before switchover

During those sessions, the Project Manager and perhaps, hired conversion specialists, provide the conversion team with instructions and guidelines for planning, organization, and implementation of the activities to come.

32.4.2 Phase 1: Application Inventory

Before you start any work on a migration you need an inventory. Start the inventory process as soon as you have made the decision to pursue migration. The work that results in a clean inventory is about determining what is in production and what is not in production on your system.

Taking inventory of your applications is a basic migration task. It does not require tremendous skill but can prove to be very laborious to complete. It is a necessary prerequisite for estimating the costs of the conversion tasks.

The objective of this repetitive task is to identify and collect the conversion inventory, transfer it to the OS/390 system, and verify that it is complete and consistent. The conversion inventory includes:

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Source code: programs, subprograms, macros, copy or include books, and so on

JCL: VSE and POWER JCL streams, standard labels, SLI and other JCL include books

∙Additional information such as job scheduling, CICS tables, VSE catalogs and VTOC listings

As a first step for the VSE to OS/390 conversion, the application inventory must be collected and verified for completeness and consistency. This allows the conversion process to begin with clean libraries, resulting in a smooth and efficient project. An iterative process, this validation is completed in two to three months. Up to four iterations of the following application inventory tasks are typically required:

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Developing/refining an inventory transfer procedure

Loading the conversion inventory into the conversion libraries

Executing the inventory validation software

Identifying any missing or unreferenced elements in the conversion inventory

Resolving the missing and unreferenced elements in the conversion inventory

It is recommended that job schedulers be taken advantage of as they can be very helpful in keeping track of what is current on the system. From the scheduler, lists of production jobs can be extracted. They can provide a good starting place from which to begin inventory validation. In CICS for example it is common to have CICS tables that are full of obsolete material.

The Application Inventory phase is complete when the application inventory contains only a small percentage of missing or unreferenced elements.

Chapter 32. Conversion Process 495

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IBM OS/390 manual Phase 1 Application Inventory
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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.
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