IBM Integration Bus, Version 10.0.0.1 Operating Systems: AIX, HP-Itanium, Linux, Solaris, Windows, z/OS


Tuning the HEAP settings on z/OS®

HEAP controls the allocation of the initial heap, controls allocations of additional heap increments, and specifies how that storage is managed.

About this task

IBM® Integration Bus requests an initial heap storage allocation and subsequent heap increments, the sizes of which depend on the type of process. For example, the DFE process requests an initial heap storage allocation of 40 Mb, with subsequent heap increments of 5 Mb. RPTOPTS can be used to generate a report of the runtime options in effect for each process.

For performance reasons, IBM Integration Bus takes the default, KEEP. For most message processing scenarios, when storage allocations are less than 5 Mb, it is more efficient to reuse storage that has been freed within the heap increment. With KEEP, the 5 Mb heap increment remains allocated, even if all of the storage segments have been released.

If storage requests frequently exceed 5 Mb, these requests are allocated directly on the heap. When the object is freed, the allocation remains on the heap, and is reused for subsequent storage requests whose size is less than, or equal to, the size of the heap allocation. Over time, the heap allocation is used for different-sized objects, and this can lead to fragmentation, which in turn can result in high storage usage. In these circumstances, consider setting the HEAP runtime environment variable for the Language Environment® to use the FREE parameter.

To set HEAP for all integration servers in an integration node, change or add the Language Environment _CEE_RUNOPTS environment variable in the component profile (BIPBPROF):
  1. Stop the integration node.
  2. Make the necessary changes to the profile.
  3. Submit BIPGEN to re-create the ENVFILE and any integration server specific ENVFILEs.
  4. Restart the integration node.
To set HEAP for a specific integration server, change or add the Language Environment _CEE_RUNOPTS environment variable in the integration server specific profile (renamed BIPEPROF):
  1. Stop the integration node.
  2. Make the necessary changes to the integration server specific profile.
  3. Submit BIPGEN to re-create the integration node ENVFILE and any integration server specific ENVFILEs.
  4. Restart the integration node.

For example, you can change the default values of KEEP to FREE in the following line:

_CEE_RUNOPTS=HEAP64(40M,5M,FREE,9M,32K,KEEP,4096,4096,FREE) 

ac34050_.htm | Last updated 2015-05-28 20:50:05