Compiling and linking COBOL programs for running under IMS
For best performance in the IMS environment, use the RENT compiler
option. RENT causes COBOL to generate reentrant code.
You can then run your application programs in either preloaded mode
(the programs are always resident in storage) or nonpreload mode
without having to recompile using different options.
About this task
Preloading can boost performance because subsequent requests for a program can be handled faster when the program is already in storage (rather than being fetched from a library each time it is needed).
For IMS programs, using the RENT compiler
option is recommended. You must use the RENT compiler
option for a program that is to be run preloaded or both preloaded
and nonpreloaded. When you preload a program object that
contains COBOL programs, all of the COBOL programs in that program object must be compiled using the RENT option.
You
can place programs compiled with the RENT option
in the z/OS® link pack area.
There they can be shared among the IMS dependent regions.
To run above the
16 MB line, an application program must be compiled with RENT.
The data for IMS application
programs can reside above the 16 MB line, and you can use DATA(31)
RENT for programs that use IMS services.
- To link program objects that contain only
COBOL programs compiled with the
RENTcompiler option, link asRENT. - To link program objects that contain a mixture
of COBOL
RENTprograms and other programs, use the link-edit attributes recommended for the other programs.
Choosing the DYNAM or NODYNAM compiler option
Language Environment® Programming Guide (Condition handling under IMS)