LSRPOOL resources

The LSRPOOL resource defines 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 may be used by VSAM to provide additional buffer capacity. For more information about MVS Hiperspace, see Creating and using hiperspaces in the z/OS MVS Programming: Extended Addressability Guide.

Up to 255 LSR pools can be defined concurrently in the system, each identified by its LSRPOOLNUM. This LSRPOOLNUM 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 that uses 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 might 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 might be incurred while pool requirements are being calculated by CICS. Another possible problem is that if files are not allocated at the time the pool is built, the data set names are not known to CICS. In this case, the pool is built based on the information available, but the subsequent performance of the system can suffer or files might 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 Setting up the CICS system definition data set for further information about CSDLSRNO and for details about calculating the buffer requirements for the CSD file.