Chapter 17. Language Environment (LE)

17.1 Introduction

This chapter introduces OS/390 Language Environment (program number

5645-001). OS/390 Language Environment is the language run-time environment distributed with OS/390.

Various strategies for migrating your applications to the Language Environment run-time are considered. These strategies depend on the programming language, the version of VSE you use, and whether you already use LE/VSE.

The information presented in this chapter is not sufficient by itself to carry out a successful migration to OS/390 Language Environment. You should study carefully the publications referred to in Table 35 on page 353 for more information. This chapter is intended to draw attention to the more obvious problems that can arise in such a migration.

17.1.1 General Comments on Language Environment

OS/390 Language Environment is the run-time environment you receive when you order your OS/390 system software.

OS/390 Language Environment provides common services and language-specific routines in a single run-time environment for C, C++, COBOL, FORTRAN, PL/I, and Assembler applications. It offers consistent and predictable results for language applications, independent of the language in which they are written.

If you are migrating to OS/390 Language Environment from a non-Language

Environment run-time environment, you should read the OS/390 Language

Environment Concepts Guide to understand the concept of Language

Environment.

17.1.1.1 A Few Words about COBOL and PL/I

With the many different environments and language products (COBOL and PL/I) here is a table to help you understand where you can run your COBOL and PL/I products.

Table 34. COBOL and PL/I: What Runs Where?

Host Operating System

Host COBOL and PL/I

Run-Time Library Support

 

Products

 

 

 

 

MVS 4.3 through MVS 5.2.2

COBOL for MVS & VM

Language Environment for

 

PL/I for MVS & VM

MVS & VM Rel 5

 

 

 

OS/390 Ver 1 Rel 1,2

COBOL for MVS & VM

Language Environment

 

PL/I for MVS & VM

element of OS/390

 

 

 

OS/390 Ver 1 Rel 3

COBOL for OS/390 & VM

Language Environment

OS/390 Ver 2 Rel 4,5

COBOL for MVS & VM

element of OS/390

 

PL/I for MVS & VM

 

 

 

 

VSE/ESA Ver 1 Rel 4

COBOL for VSE/ESA

Language Environment for

VSE/ESA Ver 2 Rel 1,2,3

PL/I FOR VSE/ESA

VSE/ESA Rel 4

 

 

 

© 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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