Chapter 12. COBOL

12.1 Introduction

This chapter introduces IBM COBOL for OS/390 and VM (program number 5648-A25), which is the COBOL compiler available with OS/390. It also outlines the differences between the three COBOL compilers that are available on VSE and COBOL for OS/390 and VM.

Various strategies for converting your VSE COBOL applications to OS/390 are considered. These strategies depend on the COBOL compiler you use on your VSE system.

The three COBOL compilers available on VSE are:

DOS/VS COBOL

program number 5746-CB1

VS COBOL II

program number 5668-958

COBOL for VSE/ESA

program number 5686-068

In addition, methods of solving problems, which can arise during a VSE to

OS/390 conversion of COBOL programs, are considered.

The information presented in this chapter is not sufficient by itself to carry out a successful conversion from COBOL under VSE to COBOL for OS/390 and VM. You should study carefully the publications referred to in Table 32 on page 252 for more information. This chapter is intended to draw attention to the more obvious problems that can arise in such a conversion.

For information on which COBOL runs on which host operating system, see

Table 34 on page 351.

12.1.1 General Comments on COBOL for OS/390 and VM

COBOL for OS/390 and VM is the COBOL compiler for your OS/390 system. COBOL for OS/390 and VM enhances the COBOL object-oriented support for OS/390 that was introduced in IBM COBOL for MVS & VM. COBOL for OS/390 and VM is based on IBM COBOL for MVS & VM, and includes such features as COBOL ANSI 85 Standard Language Support, intrinsic functions, Year 2000 Support, interlanguage communications, and the mainframe interactive debug tool full-function offering.

COBOL for OS/390 and VM uses Language Environment as its run-time environment. Language Environment provides common services and language-specific routines in a single run-time environment for C, C++, COBOL, FORTRAN, and PL/I.

If you order the Full-Function feature of COBOL for OS/390 and VM, you receive the IBM Debug Tool along with the compiler. This debugging component provides both interactive and batch debugging capabilities on the host.

© Copyright IBM Corp. 1998

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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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