The LSRPOOL resource definse the size and characteristics of the local shared resources (LSR) pool. The LSR pool is a reserve of data buffers, strings, and Hiperspace™ buffers that VSAM uses when processing access requests for certain files.
A Hiperspace buffer is a high-performance storage area in the MVS™ image. This area is used for reading and writing 4KB pages. The type of Hiperspace used by VSAM resides entirely in expanded storage, which is additional processor storage used only for paging to and from real storage.
Up to eight LSR pools can be defined concurrently in the system, each identified by its LSRPOOLID. This LSRPOOLID is used to associate a FILE with an LSR pool if that file is to use shared resources.
When the LSRPOOL definition is installed in the active system, its information is stored and used when the pool with the specified ID is next built. A pool is built when the first file using a particular LSR pool is opened, and is dynamically deallocated only when no files are currently open against that pool. This means that when an LSRPOOL definition is installed into the system it may not take effect immediately.
CICS® sets default attributes if an LSRPOOL is not defined, but you are advised to define the LSRPOOL anyway, for reasons of performance. In a production system, for example, delay may be incurred while pool requirements are being calculated by CICS. Another possible problem is that if files in the FCT are not allocated at the time the pool is built, the data set names will not be known to CICS. In this case, the pool is built based on the information available, but the subsequent performance of the system may suffer or files may fail to open.
You can associate the CSD file with a particular LSRPOOL by specifying the CSDLSRNO system initialization parameter. The default is pool 1; ensure that sufficient buffers of an appropriate size are provided to permit the CSD file to be used by CICS. See the CICS System Definition Guide for further information about CSDLSRNO and about calculating the buffer requirements for the CSD file.