Chapter 1. Why Customers Migrate

This chapter discusses the following topics:

1.2, Traditional Reasons for Migrating

1.3, Functional Reasons for Migrating to OS/390

1.1 A Synopsis of This Book

What do I need to read?

Executives: Read the following:

Part 1, ªPlanning the Migration - An Introductionº on page 1 Part 8, ªMigration Experienceº on page 527

System Programmers: Read the following:

Part 1, ªPlanning the Migration - An Introductionº on page 1

Part 2, ªConverting the VSE Operating System to the OS/390 Operating Systemº on page 67

Part 4, ªConverting VSE Utilities to OS/390 Utilitiesº on page 373 Part 5, ªSetting Up the Migration Environmentº on page 399 Part 6, ªRunning Your OS/390 Systemº on page 435

Operators: Read the following:

Part 6, ªRunning Your OS/390 Systemº on page 435

Application Programmers: Read the following:

Part 3, ªConverting VSE Languages to OS/390 Languagesº on page 247 Part 7, ªConverting your Applicationsº on page 479

This document is divided into nine parts:

Part 1, Planning the Migration - An Introduction

The scope of effort required to migrate from VSE to OS/390 will vary from one organization to another. Many factors must be considered when making the decision of when and how to migrate. This part discusses the reasons for migrating, factors to consider when sizing the effort, and developing a migration plan.

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

In this part the conversion of the VSE system including JCL, data storage methods, CICS, ICCF, telecommunications, spooling, and printing is discussed. Additionally, a comparison of the use of CMS and TSO is presented for those currently running VSE under VM.

Part 3, Converting VSE Languages to OS/390 Languages

Conversion of the various language compilers to their equivalent OS/390 language is discussed in this part. Also, any execution time differences are discussed.

© Copyright IBM Corp. 1998

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IBM OS/390 Why Customers Migrate, Synopsis of This Book, What do I need to read?, System Programmers Read the following

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.