Please contact your local IBM Representative for more information on how to access IBM manuals via the INTERNET.

Another useful INTERNET location ′http://www.hursley.ibm.com/cics′, is the CICS home page.

The CICS Internet Home page provides a service/support segment that allows easy access to a wide range of material that complements the CICS Family of products. As part of the Service and Support segment, user forums are available for CICS migration tidbits and Qs and As.

Also, the CD-ROM collect kits, can be a useful source for IBM manuals. The Collection Kit for Transaction Processing and Data Products, SK2T-0730 includes the unlicensed manuals except for:

∙

∙

CICS Master Index, SC33-1704

CICS Transaction Server for OS/390 Licensed Program Specifications, GC33-1707.

6.1.3 General Compatibility Comments

One of the strengths of the CICS products is the portability of the Command Level API between operating systems. However, applications that include Report Controller API cannot be migrated and there is no printer and spool file manipulation facilities available in the CICS TS environment. Thus, you should prepare alternate solutions (such as, MVS LAN/RES, user written programs, TCP/IP print daemons, vendor packages) if your users require the same or similar functions or identify the service as no longer available (the sooner the better) to the users.

CICS system facilities will differ between the two operating systems. Facilities based upon the operating system architecture and product-unique (VSE, MVS) functions will have to be re-worked during the conversion to OS/390. One significant change will be the effects on performance and tuning. OS/390 will accommodate additional resources and larger buffer pools resulting in I/O reductions, improved response times, and higher transaction rates. It will also introduce new tuning controls such as the MVS Systems Resource Manager (SRM) that can provide more consistent response times. For these reasons, a stress test of the CICS/MVS system should be a part of the overall MVS migration plan. The major differences between VSE and MVS CICS application programs can be attributed to unique facilities provided by the programming languages or the operating systems. As long as CICS application programs have adhered to standard CICS programming interfaces outlined in the CICS Application Programmer′s Reference Manual(s) (APRM), the migration or conversion effort should be minimal. In most cases only a CICS/MVS translation and compilation will be required. If the applications are using non-CICS functions such as GET/PUT or COMREG, they may require significant recoding.

6.1.4 Virtual Storage Considerations for MVS

To minimize change during the migration to MVS, the general recommendation is to bring multiple CICS/VSE systems across to MVS the same as they are in the VSE environment. That is, if you have two or more independent production CICS systems under VSE, you would want multiple independent production CICS systems under MVS. MVS/ESA provides considerable virtual storage constraint relief for CICS systems. This is due to the ability to place almost all management modules, and many control blocks above the 16 megabyte line. In addition,

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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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