ALL31 (wizard)
IBM defaults to and strongly recommends optimizing for AMODE 31 routines, specified
by ALL31(ON). When ALL31(ON) is specified :
- AMODE
switching across calls to Language Environment common run-time routines is
minimized. For example, no AMODE switching is performed on calls to Language Environment
callable services.
- In COBOL, EXTERNAL data is allocated above the 16 MB line when available.
- In CICS, Language Environment allocates storage for the common anchor area (CAA) and
other control blocks.
You must specify ALL31(OFF) by enabling the checkbox if your applications contain one of
the following programs :
- A Fortran program that has not been compiled with VS FORTRAN Version 1 or Version 2
that requires 24-bit addressing
- A VS COBOL II NORES program
- A non-CICS OS/VS COBOL program
Otherwise, use the default of ALL31(ON). If you have programs that require you to use
ALL31(OFF), it is recommended that you update them to take advantage of the ALL31(ON)
performance considerations noted below. ALL31(OFF) has the following implications :
- AMODE switching across calls to Language Environment common run-time routines is
performed. For example, AMODE switching is performed on calls to Language Environment
callable services.
- In COBOL, EXTERNAL data is allocated in storage below the 16 MB line.
- STACK will automatically be set to STACK(,,BELOW).
- Language Environment will preallocate BELOWHEAP instead of ANYHEAP storage.
Performance Consideration :
- If your application consists entirely of AMODE 31 routines, it will run faster and use
less below-the-line storage with ALL31(ON), since mode switching code is not required.
Notes :
- When an application is running in an
XPLINK environment, either as specified by the
XPLINK(ON) option or by an initial program that contained at least one XPLINK-compiled
part, the ALL31 run-time option will be forced to ON. No AMODE 24 routines are allowed
in an enclave that uses XPLINK. No message will be issued to
indicate this action.
- z/OS UNIX System Services consideration : The ALL31 option applies to the enclave.