Warning: When you migrate your CSD entries you must ensure that you do not copy over IBM supplied definitions in groups that you have defined. The reason is that some of the groups and resources were changed and/or deleted. Thus, you should see that your user groups with IBM defined resources are copied from the newly defined CSD. Once, you have imported your defined resources into the CSD for MVS, be cognizant of changes via the ALTER command, the default attributes and/or new attributes may not be what you desire. To illustrate, the SESSION resource definitions allows the send and receive prefixes to default. CICS creates the last three characters of the session names from the alphanumeric characters A through Z, and 1 through 9. These

three-character identifiers begin with the letters AAA, and continue in ascending sequence until the number of session entries reaches the limit set by the SENDCOUNT or RECEIVECOUNT value.

6.1.7.2 RDO

Here are items to consider with the use of RDO on your CICS/ESA system:

∙Be sure that all user defined TRANSACTION resources specify the attribute (SPURGE). SPURGE must be set to purge transaction from the system and to detect loops.

∙CICS-supplied transactions have changed (for example, CSSN and CSSF are CESN/CESF). CICS TS removed transactions CSMT, CSOT, CSSF, CSSN, and CSST. Please refer to your CICS Supplied Transaction, SC33-1686 for more details.

Below are examples of resources and/or attributes changes:

TRANSACTION/TCLASS

is replaced by the TRANCLASS parameter, within the new TRANCLASS resource definition.

CONNECTION/SECURITYNAME(MRO)

is obsolete on MRO connections. To specify bind-time and link security for MRO connections, you must define appropriate RACF (or another ESM) security profiles.

CONNECTION/PROTOCOL

the scope of this parameter is extended for the external CICS interface (EXCI). This parameter allows client programs (batch programs) the ability to access CICS services.

PROGRAM/EXECKEY

the effect of this parameter is extended for transaction isolation. With transaction isolation active, a user-key program has read and write access to the user-key task-lifetime storage of its own task only, and to any shared DSA storage, if its transaction is defined with ISOLATE(YES).

SESSIONS/RECOVOPTION

this parameter is extended to cover VTAM persistent sessions. In earlier releases of CICS it was meaningful for CICS regions running with XRF only.

SESSIONS/RECEIVEPFX/SENDFX

you no longer need to specify send and receive prefixes on MRO session definitions.

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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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