Bit 0

SYSIPT overrides yes or no.

All overrides are passed as

 

 

execution parameters to DFHSIP.

 

 

 

Bit 1

This is no longer required for

 

 

CICS/OS or CICS/VSE 1.6 or later.

 

 

 

 

Bit 2

Operator prompt for overrides yes

The parameter CONSOLEas the

 

or no.

last PARM in the EXEC statement

 

 

indicates that the operator is to

 

 

be requested to enter overrides.

 

 

 

Bit 3

If Dump returns a nonzero return

CICS/MVS DUMP is directed to

 

code when writing to the

MVS SYS1.DUMxx only.

 

SYSDUMP data set and an IDUMP

 

 

will be produced on SYSLST.

 

 

 

 

Bits 4-5

Are not currently used.

 

 

 

 

Bits 6-7

Reserved for DL/I.

Not required for IMS.

 

 

 

6.1.12 Application Programming

Command-level programs are upward compatible at both source and object level, provided they conform to the interface as defined in the Application Programmers Reference manual. However, it is imperative that you understand upward compatible does not constitute that your program will continue to run on your CICS/VSE system (that is, programs reassembled and linkedited to CICS TS are not guaranteed to run on CICS/VSE). Hence, you should be sure that your System Management/Change Management and Roll-back plan accounts for this situation.

Notes:

1.CICS 1.7 applications can be relinkedited on MVS, but you should not expect the programs to function (consider recompiling programs).

2.DOS PL/I applications do not function on MVS, hence you should consider rewriting DOS PL/I to a PL/I supported level.

Macro-level programs are not supported on MVS. You can convert your macro-level programs to command-level using the CICS AMA conversion aid to assist with the conversion.

CICS programs written with LE support are generally object module compatible between VSE/ESA and OS/390. However, there are some commands where CVDA/REP values are different, thus retranslation, recompile is necessary. CICS command-level (non-LE) programs which have adhered to the CICS documented Application Programming Interfaces (API) are generally source compatible between VSE/ESA and OS/390.

Source programming conversion should be minimal with only language differences to be resolved, such as COBOL reserved words. The presence of any of the following conditions may substantially increase the effort:

Programs that start a BROWSE operation, then read for UPDATE. For a file accessed in non-RLS mode, CICS should return an INVREQ condition. Updating and deleting records in a browse is only supported for VSAM files opened in RLS mode.

EXEC CICS ADDRESS CSA commands are no longer supported.

150VSE to OS/390 Migration Workbook

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IBM OS/390 manual Application Programming

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.