Chapter 9. Telecommunications Subsystems

VSE and OS/390 platforms rely on the same set of communications products and protocols. Although the product sets are the same, some differences exist in product implementation and usage. The differences are primarily related to the operating systems and their file structures. This chapter will discuss the similarities and differences between VSE and OS/390 environments for the following telecommunications products:

9.1, ACF/VTAM

9.2, ACF/NCP

9.3, BTAM

9.4, Migrating TCP/IP

9.5, MQSeries

9.1 ACF/VTAM

The most recent release of VTAM for OS/390 is VTAM Version 4 Release 4.1. However, this product is not available separately and is packaged together with TCP/IP as the OS/390 eNetwork Communications Server Release 5. Previous releases of VTAM up to Version 4 Release 4 were available as a stand-alone product, 5695-117. At the time of writing, supported releases of VTAM for VSE include Version 3 Release 4 and Version 4 Release 2.

The functions of VTAM for OS/390 are, with one major exception, a superset of the functions of VTAM for VSE. The main differences are related to those between the operating systems, rather than to any differences in the way that SNA networks are defined and configured. However, OS/390 does not provide a facility such as the VSE Interactive Interface (II) to guide you through SNA resource definitions. You must code new network resource definitions from scratch, although you should be able to use most of your existing VSE definitions without change. The exception would be the definition of new resources required for networking configuration changes associated with the migration project.

The following subsections summarize the tasks you will have to perform to install and set up an OS/390 VTAM system. For further details we recommend the following product manuals (those quoted are for Communications Server for OS/390 Release 5):

eNetwork Communications Server for OS/390 Installation and Migration Guide, SC31-8622

eNetwork Communications Server for OS/390 Network Implementation Guide, SC31-8563

eNetwork Communications Server for OS/390 Resource Definition Reference, SC31-8565

eNetwork Communications Server for OS/390 Resource Definition Samples, SC31-8566

eNetwork Communications Server for OS/390 Programming, SC31-8573

eNetwork Communications Server for OS/390 Customization, LY43-0110

© Copyright IBM Corp. 1998

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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.