Creating and registering buffer pools

Upon application request, CSM can create buffer pools based on the size and types listed in Table 1. A total of 15 CSM buffer pools can be created, one for each storage type and buffer size.

The structures that maintain the storage pools are created as a result of the first IVTCSM REQUEST=CREATE_POOL macroinstruction issued by a CSM user (this could be VTAM® or a host application). The pool might or might not already exist. In either case, the application that issues the CREATE_POOL request is a registered user and can obtain buffers from that pool. CSM returns a token in the RETPTOKN parameter, which the application uses on subsequent requests buffer requests from that pool.

An application can specify buffer pool tuning parameters on the CREATE_POOL request. See CSM buffer pool expansion and contraction for more information.

Guideline: Where possible, programs should use CSM data space instead of ECSA. Furthermore, use of 64-bit backed CSM data space is preferred to 31-bit backed CSM data space. Use data space instead of ECSA and 64-bit backed data space instead of 31-bit backed data space to benefits overall system performance.