8.1.7.2 Backout Utility/Disk Logging

IMS/ESA supports both DASD and tape logging in batch. The archive utility DFSUARC0, is used to copy disk logs to tape. Disk is acceptable as input to all IMS/ESA utilities including backout.

8.1.7.3 UPSI

The use of the UPSI byte is not supported by MVS. The equivalents for the various bits are:

∙

∙

∙

∙

∙

Bit 0: Reading of parameter statement.

This function is replaced with parameters in the EXEC statement of the MVS JCL.

Bits 1-3: Available to the application programmer.

If these bits have been used, the application programs must be modified to the MVS standard established for the installation.

Bit 5: Storage dump request if STXIT active.

The presence of the SYSUDUMP DD statement determines if a dump is to be taken in MVS.

Bit 6: Log function active or inactive.

The IEFRDER DD statement being set to DD DUMMY is the only way to avoid logging with IMS/ESA. If Data Base Recovery Control (DBRC) is used, logging is forced for all batch problems using a PSB with update intent on any DBRC registered database. Thus, you may not specify IEFRDER DD DUMMY.

Bit 7: Setting STXIT active or inactive.

There is no direct equivalent required in MVS. The SPIE= parameter in the IMS/ESA EXEC statement relates to the handling of an application program SPIE during a CALL. For more information see the IMS/ESA System Programmers Guide, procedures DBBATCH and DLIBATCH.

8.1.7.4 DL/I Parameter Statement

The functional equivalents of this statement in IMS/ESA are implemented through either EXEC statement PARMs or entries in the DFSVSMnn member of IMSESA.PROCLIB. This is located through the DFSVSAMP DD statement. The following applies only to VSAM databases. For OSAM options and more detail on VSAM, see the IMS/ESA Installation Guide and the IMS/ESA System Administration Guide.

DL/I Parameter

IMS/ESA Equivalent

progname

PARM on EXEC

psbname

PARM on EXEC

buf

# entries DFSVSMnn

HDBFR

VSAM Subpool statement in DFSVSMnn

HSBFR

Uses VSAM Subpool

TRACE =

DFSVSMnn OPTIONS or/and DLITRACE

ASLOG =

OPTIONS LTWA=

LOG =

IEFRDR DD data set

RC=

not supported

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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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