12.1.2 Comparison of IBM COBOL Compilers

 

DLL Support

 

Extensions for:

 

Object-Oriented COBOL

 

C Interoperability

 

 

Intrinsic Functions

Intrinsic Functions

Amendments to ′85 Std

Amendments to ′85 Std

Support for:

Support for:

Language Environment

Language Environment

Debug Tool

Debug Tool

 

 

 

COBOL 85 Standard

COBOL 85 Standard

COBOL 85 Standard

 

No Intrinsic Functions

 

 

 

Structured Programming

Structured Programming

Structured Programming

 

DBCS Support

DBCS Support

DBCS Support

 

National Language

National Language

National Language

 

Improved CICS Interface

Improved CICS Interface

Improved CICS Interface

 

31-bit Addressing

31-bit Addressing

31-bit Addressing

 

Reentrancy, Fast Sort

Reentrancy, Fast Sort

Reentrancy, Fast Sort

 

Optimizer, SAA Flagging

Optimizer, SAA Flagging

Optimizer, SAA Flagging

 

Interactive Debugging

Interactive Debugging

Interactive Debugging

 

(Full-screen mode)

(Full-screen mode)

(Full-screen mode)

 

 

 

 

COBOL 74 Standard

COBOL 74 Compatibility

COBOL 74 Compatibility

COBOL 74 Compatibility

74 Std FIPS Flagging

85 STD FIPS Flagging

85 STD FIPS Flagging

85 STD FIPS Flagging

 

Dynamic Loading

Dynamic Loading

Dynamic Loading

Batch Debugging

Batch Debugging

Batch Debugging

Batch Debugging

 

 

Interactive Debugging

Interactive Debugging

 

 

(Line Mode)

(Line Mode)

 

 

 

 

DOS/VS COBOL

VS COBOL II

COBOL for VSE/ESA

COBOL for OS/390 & VM

Figure 18. Comparison of IBM COBOLs

COBOL for VSE/ESA is source-compatible with COBOL for OS/390 and VM. Your COBOL for VSE/ESA programs should compile successfully without change under COBOL for OS/390 and VM.

VS COBOL II programs may require some changes to enable them to compile under COBOL for OS/390 and VM, but the changes will probably not be extensive.

DOS/VS COBOL programs will require modification before they will compile under COBOL for OS/390 and VM.

12.2 VSE to OS/390 Migration Considerations

The strategy you follow to migrate your COBOL applications to OS/390 depends on the COBOL compiler you are using in VSE, and the version of VSE you are running.

Up to and including VSE/ESA version 1 release 1, the only COBOL compiler available was DOS/VS COBOL. The conversion aid, COBOL and CICS Command Level Conversion Aid for VSE (CCCA/VSE) will not execute in this environment, but CCCA/MVS can be used.

Under VSE/ESA version 1 releases 2 and 3, the COBOL compilers available are DOS/VS COBOL and VS COBOL II; CCCA/VSE is available to aid the conversion process.

250VSE to OS/390 Migration Workbook

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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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