Previous topic |
Next topic |
Contents |
Contact z/OS |
Library |
PDF
BELOWHEAP z/OS Language Environment Customization SA38-0685-00 |
|
BELOWHEAP controls the allocation of library heap storage that must be located below the 16MB line. The heap controlled by BELOWHEAP is intended for items such as control blocks used for I/O.
Syntax .-FREE-. >>-BELOWHEAP--=--(--(--init_size--,--incr_size--,--+-KEEP-+-----> .-OVR----. >--)--,--+-NONOVR-+--)-----------------------------------------><
CICS considerationsThe default increment size under CICS is 4080 bytes, rather than 4096 bytes, to accommodate the 16 bytes CICS storage check zone. Without this accommodation, an extra page of storage is allocated (only when the storage allocation is below the 16MB line). z/OS® UNIX considerationsThe BELOWHEAP option applies to the enclave. Usage notesBoth the initial size and the increment size are rounded to the nearest multiple of 8 bytes. If you specify BELOWHEAP(0), the initial BELOWHEAP is obtained on the first use and will be the increment size. Performance considerationsBELOWHEAP improves performance when you specify values that minimize the number of times that the operating system allocates storage. The RPTSTG run-time option generates a report of storage your application uses while running. You can use its numbers to help determine what values to specify. For more information
|
Copyright IBM Corporation 1990, 2014
|