DATA(24) and DATA(31)

Default
DATA(31)
Recommended
DATA(31), if the program doesn't need to call and pass parameters to AMODE 24 subprograms.
Reasoning

Using DATA(31) with your RENT program will help to relieve some below the line virtual storage constraint problems. When you use DATA(31) with your RENT programs, most QSAM file buffers can be allocated above the 16MB line. When you use DATA(31) with the runtime option HEAP(,,ANYWHERE), all non-EXTERNAL WORKING-STORAGE and non-EXTERNAL FD record areas can be allocated above the 16MB line.

With DATA(24), the WORKING-STORAGE and FD record areas will be allocated below the 16 MB line.

Notes:
  • For NORENT programs, the RMODE option determines where non-EXTERNAL data is allocated.
  • See QSAM buffers for additional information on QSAM file buffers.
  • See ALL31 for information on where EXTERNAL data is allocated.
  • LOCAL-STORAGE data is not affected by the DATA option. The STACK runtime option and the AMODE of the program determine where LOCAL-STORAGE is allocated.

Note that while it is not expected to impact the performance of the application, it does affect where the program's data is located.

related references
DATA (Enterprise COBOL for z/OS® Programming Guide)