On z/OS®, the Language Environment® product provides a common environment for all conforming high-level language (HLL) products. An HLL is a programming language above the level of assembler language and below that of program generators and query languages. z/OS Language Environment establishes a common language development and execution environment for application programmers on z/OS. Whereas functions were previously provided in individual language products, Language Environment eliminates the need to maintain separate language libraries.

An application is a collection of one or more programs cooperating to achieve particular objectives, such as inventory control or payroll. The goals of application development include modularizing and sharing code, and developing applications on a workstation-based front end.

In the past, programming languages had limited ability to call each other and behave consistently across different operating systems. This characteristic constrained programs that wanted to use several languages in an application. Programming languages had different rules for implementing data structures and condition handling, and for interfacing with system services and library routines.

With Language Environment, and its ability to call one language from another, z/OS application programmers can exploit the functions and features in each language.