an MQSeries termination, and automatic resource resynchronization after a restart.

The CICS adapter is supplied with MQSeries as the CICS transaction CKQC.

9.5.1.4 Data Sets

MQSeries for VSE/ESA uses the following data sets:

∙the System Setup file: a VSAM ESDS file containing system setup information. It is only used once to initialize the System Configuration file.

∙the System Configuration file: a VSAM KSDS file. It initially contains system definitions, messages, names of MQSeries maps and programs and so on. It will be updated whenever the user defines additional MQSeries objects such as queues and channels.

∙Queue data sets: VSAM KSDS files to hold messages.

MQSeries for MVS/ESA uses the following data sets:

∙

∙

∙

Page sets to store messages and definitions.

A page set is a linear VSAM data set that has been formatted for use by MQSeries for MVS/ESA. Each page set is identified by a page set ID (PSID), an integer in the range 00 through 99. In particular, MQSeries for MVS/ESA uses page set 00 to store queue definitions and other important information relevant to the queue manager.

Log data sets to log data and events.

MQSeries for MVS/ESA records all persistent messages in the active log. When the active log is full, MQSeries for MVS/ESA switches to the next available log data set. Each active log data set is a single-volume, single-extent VSAM entry-sequenced data set (ESDS).

If archiving has been switched on during customization, MQSeries for MVSE/ESA copies the contents of a full active log to an archive log when it switches logs. The archive logs can be a data set on a direct access storage device (DASD) or on magnetic tape. The archive log consists of up to 1000 sequential data sets. Each data set can be cataloged using the Integrated Catalog Facility (ICF).

MQSeries for MVS/ESA allows you to have either single logging or dual logging.

The boot strap data set is a VSAM key-sequenced data set (KSDS) that holds information needed by MQSeries for MVS/ESA. It contains an inventory of all active and archived log data sets known to MQSeries for MVS/ESA.

No migration of the data sets used by MQSeries for VSE/ESA to those used by MQSeries for MVS/ESA is supported.

To set up MQSeries for MVS/ESA you need to define and populate the required data set from scratch.

You can use the information on the size of your VSE/ESA data sets to estimate the space required under OS/390.

No facility exists to move messages from a VSE/ESA queue to a queue under OS/390. Therefore, you should make sure that all your queue entries have been processed under VSE/ESA before you switch to the OS/390 system.

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IBM OS/390 manual Data Sets
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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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