Preface

The purpose of this document is to provide information and guidance to personnel involved in a VSE to OS/390 operating system change; that is, a VSE to OS/390 migration.

The primary focus is on VSE program and file conversions, and on operational differences between the two systems. Chapters on each of the source languages are included. DB/DC conversions, and operational differences between POWER and JES2 are also addressed.

Within each chapter, not only are the differences pointed out, but OS/390 implementation and suggested use recommendations are made wherever possible. These recommendations can help the migrating customer ²better² design their use of OS/390.

Throughout this document, the term MIGRATION refers to the entire process of transition from a VSE environment to an OS/390 environment. The term CONVERSION describes the process of translating and updating VSE applications and data to meet the requirements of OS/390.

The Team That Wrote This Redbook

This redbook was produced by a team of specialists from around the world working with the International Technical Support Organization Poughkeepsie Center.

Our thanks to Judith Jay for bringing a renewed focus to the issues, concerns and effort required to migrate from VSE to OS/390.

Redbook Builders and Key Contributors

Cliff Bays IBM, Endicott

Bimshire Davis IBM, Chicago

Don Durand IBM, Poughkeepsie

Dan Ebaugh IBM, Gaithersburg

Patrick Fournier Managing Partner, Automated Migration Services, Walnut

Creek, CA

Dave Greenough IBM, Vermont

John Hutchinson IBM, Gaithersburg

Dan Janda IBM, Endicott

Judith Jay IBM, White Plains

Kevin Jones IBM, Endicott

Herbert Kratzer IBM, Germany

Tom Plunkett Senior Director of Systems Engineering, Automatic Data

Processing, Inc., Roseland, NJ

Gilbert Saint-flourTechnical Manager, Automated Migration Services,

Livingston, NJ

John Sutera IBM, Endicott

Guenter Weigelt IBM, Germany

© Copyright IBM Corp. 1998

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IBM OS/390 manual Preface, Team That Wrote This Redbook, Redbook Builders and Key Contributors

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.