What is Language Environment (LE) in Mainframe

If a program want to invoke another program, then both the programs should run within the same run time environment. That way memory acquired by main program can be accessed by sub-program and vice-versa, and if the sub-program generates any exception, the main program would be able to intercept that exception and proceed accordingly.

In PC, we cannot invoke a VB program from C program and vice versa. Both the languages follow their own convention to pass arguments, they have their own run time environment which handles the memory management, exception handling and built-in functions. Because of this inconsistent run time environment in PC, you can not invoke a program coded in one language from a program coded in another language.

But in mainframe, we have common run environment for all the languages. We call this common run environment as Language environment (LE). All the compilers in mainframe, generates LE compatible load modules. LE is an element of the mainframe operation system. Because of LE, a COBOL program can invoke a Assembler program just like any other COBOL program. Similarly a FORTRAN program can invoke a PL/I program. All the high level language programs runs on the top of LE.

LE provides a robust platform to develop applications. A COBOL program can invoke an Assembler program and make use of the best features of Assembler language and thus languages can complement each other. In addition, programmers with various language skills, could work together to build applications with component programs written in a variety of languages.

Since library routines are common, the applications behave consistently and predictably.