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.
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
RENT
compiler option, link asRENT
. - To link program objects that contain a mixture
of COBOL
RENT
programs 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)