LIBSTACK (CICS)
LIBSTACK controls the allocation of the
thread's library
stack storage. This stack is used
by Language Environment and HLL library routines that require save areas below the 16 MB line.
LIBSTACK has the following suboptions :
- initial size : the minimum initial size library stack segment, rounded
to the nearest 8 bytes of contiguous storage
minimum initial size : 32 bytes, maximum intial size : 32 K
- initial size units : the units that initial size is specified in (bytes, K)
- increment size : the minimum size of any subsequent
increment to the library stack
area, rounded to the nearest 8 bytes.
minimum initial size : 32 bytes, maximum intial size : 32 K
- increment size units : the units that increment size is specified in (bytes, K)
- KEEP or FREE :
FREE specifies that storage allocated to LIBSTACK increments is released when the last of
the storage in the library stack is freed. The initial library stack segment is not
released until the enclave terminates.
KEEP specifies that storage allocated to LIBSTACK increments is not released when
the last of the storage in the library stack is freed.
Notes :
- Note that the increment size may not represent the actual amount of allocated storage, if
the a routine needs a larger amount of storage for a stack frame. The amount allocated will
always be the larger value of the increment specified and the amount requested.
- The default increment size under CICS is 4080 bytes, rather than 4096 bytes, to accomodate the 16 byte CICS storage check zone. Without this accomodation, an extra page of storage is allocated (only
when the storage allocation is below the line).
- If ALL31(ON) is specified, LIBSTACK will be allocated above the 16 MB line.
- z/OS UNIX System Services consideration : The LIBSTACK option sets the library
stack characteristics on each thread. The recommended settings for LIBSTACK under z/OS UNIX are
4K,4K,FREE