17.1.2 Conceptual Differences between LE/VSE and OS/390 LanguageEnvironment
There are some conceptual differences between LE/VSE and OS/390 Language
Environment. These differences do not affect the running of your migrated
LE/VSE applications in an OS/390 Language Environment but you may want to
take advantage of the extra facilities offered by the OS/390 Language
Environment. For more information, refer to the

LE/VSE Concepts Guide Release

4

, or

LE/VSE Concepts Guide Release 1

, and the

OS/390 Language Environment

Concepts Guide

.
•OS/390 Language Environment supports multithreading. LE/VSE supports
only single threading.
•OS/390 Language Environment supports applications consisting of one or
more processes. LE/VSE supports only a single process for each application
that runs in the common run-time environment.
•OS/390 Language Environment supports multiple threads within an enclave.
LE/VSE supports only a single thread within an enclave.
17.2 VSE to OS/390 Migration Considerations
The strategy you follow to migrate your run-time environment to OS/390 depends
on the programming language, the run-time environment you are using in VSE,
and the version of VSE you are running.
If you are using an LE/VSE-conforming language, you may be able to transfer
your compiled object code to OS/390 from your VSE system, link-edit it with
OS/390 Language Environment and run it there without further change. See
below for a list of LE/VSE-conforming languages.
Whatever language, run-time environment or version of VSE you are running,
you will at least have to relink your object code in OS/390. It is not possible to
transfer phases from your VSE libraries to OS/390.
17.2.1 LE/VSE-conforming Languages
An LE/VSE-conforming language is any high-level language (HLL) that adheres to
the LE/VSE common interface.
There are three LE/VSE-conforming languages:
C for VSE/ESA program number 5686-A01
COBOL for VSE/ESA program number 5686-068
PL/I for VSE/ESA program number 5686-069
These languages require LE/VSE to be available at compile-time, as well as
link-edit and run-time. LE/VSE requires VSE/ESA version 1 release 4, or VSE/ESA
version 2 or later. C for VSE/ESA requires LE/VSE 1.4. You cannot compile or run
C for VSE/ESA programs under LE/VSE 1.1.
Any HLL not listed above, is known as a non-LE/VSE-conforming language.
These include C/370, DOS/VS COBOL, VS COBOL II, DOS PL/I and VS FORTRAN.
352 VSE to OS/390 Migration Workbook