12.3.2 DOS/VS COBOL Programs Containing REPORT WRITER Statements

COBOL for OS/390 and VM does not support the REPORT WRITER statements. However, you can keep your REPORT WRITER statements by using the COBOL Report Writer Precompiler prior to the new compiler. Alternatively, you can use the COBOL Report Writer Precompiler to convert your REPORT WRITER statements to COBOL code.

12.4 DOS/VS COBOL and COBOL for OS/390 and VM Language Differences

Note

The following discussion on programming differences is relevant only to differences between DOS/VS COBOL and COBOL for OS/390 and VM.

12.4.1 Common COBOL Coding Problems

The following are some common DOS/VS COBOL coding ¢ mistakes¢ that will not work in OS/390. They may be logic errors or ¢ invalid¢ coding that DOS/VS COBOL nevertheless allowed. They will probably not be converted or notated by a conversion tool.

This is not meant to be an exhaustive list, but only some of the more common problems that can arise. You should read carefully the relevant chapters of either the COBOL for VSE/ESA Migration Guide or the COBOL for OS/390 and VM Compiler and Run-Time Migration Guide to determine the DOS/VS COBOL language elements that have changed or are no longer supported in COBOL for OS/390 and VM.

∙Referencing a file′s (or printer′s) I/O area before the file (or printer) is OPENed will result in a system 0C4 abend in OS/390.

∙

∙

Referencing a file′s (or printer′s) I/O area after the file (or printer) is CLOSEd will result in a system 0C4 abend in OS/390.

A ¢ STOP RUN¢ statement should not be embedded within a SORT procedure. In OS/390, sorts must end before a STOP RUN can be requested.

∙

∙

Level-88 statements that define non-numeric literals, when the literals are not enclosed in quotes, are invalid.

For example:

05 PRIMARY-FIELD PIC XX.

88 FIELD1 VALUES ARE 60 61 62.

88 FIELD2 VALUES ARE 50 51 52.

Using COBOL for OS/390 and VM you will receive message:

IGYGR1239-S Level-88 ²VALUE² literal ²61² was not compatible with the data category of the conditional variable. The literal was discarded.

The literal values (60 61 62 50 51 52) must be enclosed in quotes. DOS/VS COBOL ignored the requirement for the quotes and processed the literals as the programmer intended.

Redefinitions of level-01 entries in the File Section are not allowed. When more than one level-01 entry follows a file description entry, the redefinition is implicit.

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IBM OS/390 manual Common Cobol Coding Problems, Primary-Field Pic, FIELD1 Values are 60 61 FIELD2 Values are 50 51
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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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