to SYSLST, access to CICS system control blocks. You should consider what impact each of the removed service or support will have on your migration.

Macro-level programs

You need to convert macro-level programs to command level. Please account for and anticipate the additional CPU requirements for the converted programs.

BTAM devices and controllers

As an alternative consider the supported devices of ACF/VTAM and/or TCP/IP. TCP/IP communications are also supported using either the ONC RPC function or the CICS Web interface. Please review the CICS ONC RPC Guide, SC33-1778 and CICS Internet and External Interface, SC33-1944 for more detail on the concepts and use of ONC RPC.

CICS internal security and signon table

Since the internal security signon table is no longer supported, you can migrate user data from an existing signon table (SNT) to the RACF database.

If you are using CICS for VSE/ESA 2.3, you can use the security migration aid to assist you with the migration of your CICS internal security definitions to an environment where their resource(s) can be defined with RACF.

Nucleus load table

CICS management modules are restructured into DOMAINS. In the process, CICS removed this function.

Application load table

CICS management modules are restructured into DOMAINS. Thus, CICS removed the possibility of you aligning application programs. You can still specify program residency via the RDO. However, you should review the Resource Definition Guide to get a better understanding as to where this parameter is applicable.

Journaling to tape service

CICS TS Support for single MVS image systems is through DASD logging. DASD logging is for single image in sysplex configurations without a coupling facility (non-parallel sysplex) and stand-alone OS/390 systems (single-system sysplex). Also, CICS TS supports coupling facility logging. The point to remember is that you must review your journaling requirements and operation procedure for CICS TS journal support.

Shutdown statistics to SYSLST

There are numerous changes to CICS statistics records, generally as a result of the new domains created in CICS/ESA, such as the transaction manager domain. As a result, a number of statistics DSECTs, previously supplied as copybooks, are obsolete and withdrawn. Therefore, you should consider alternatives to printing CICS shutdown statistics.

There is a PLT program in SDFSAMP called DFH$STED which can be placed in the startup PLT to stagger writing shutdown or interval statistic to SMF. You should note that without this staggering, you could experience a significant performance problem if interval stats or shutdown occurs in many regions at the same time.

Chapter 6. CICS 137

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IBM OS/390 Macro-level programs, Btam devices and controllers, Cics internal security and signon table, Nucleus load table
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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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