BLDVRP: Build the VSAM resource pool

Use the BLDVRP command to request CICS® VR to issue the build VSAM resource pool (BLDVRP) VSAM macro for a forward-recovery run.

This causes VSAM to generate a local shared resource (LSR) pool, which is a set of index and data buffers that are to be shared by all VSAM files participating in the CICS VR run. You can improve the performance of your CICS VR run by using the BLDVRP command to specify the size and number of VSAM buffers.

Specify BLDVRP with no keywords to have CICS VR automatically calculate the LSR buffer space for you. In this case, CICS VR calculates the buffer space automatically and issues the DWW0617I message indicating the size and number of buffers that are calculated.

Format

Read syntax diagramSkip visual syntax diagramBLDVRPB512(number of buffers)B1K(number of buffers)B2K(number of buffers)B4K(number of buffers)B8K(number of buffers)B12K(number of buffers)B16K(number of buffers)B20K(number of buffers)B24K(number of buffers)B28K(number of buffers)B32K(number of buffers)

Keywords

No keywords
BLDVRP with no keywords specifies that CICS VR automatically calculates the appropriate number of buffers for each buffer pool based on the VSAM spheres being recovered in the CICS VR recovery job.
B512(number of buffers)…,B32K(number of buffers)
Defines the size and number of buffers in each buffer pool within the VSAM resource pool. A VSAM file uses the buffer pool whose buffer size exactly matches the file's CI size, or if this CI size is not available, the buffer pool with the next–larger buffer size. You can only specify each buffer pool once.
number of buffers
Specifies the number of buffers to be defined for each buffer pool. The number of buffers must be in the range 3–65 535.

Usage Notes

Consider the following information when you use the BLDVRP command:
  • Use the BLDVRP command to improve the performance of VSAM for a CICS VR run.
  • The LSR is divided into subpools, each representing a different control interval size. Before reading the data and index control intervals, the buffers are scanned to see whether the request can be satisfied from the LSR pool. The BLDVRP command improves the performance of VSAM by reducing I/Os to disk.
  • You can specify only one BLDVRP per CICS VR step.
  • The BLDVRP command is optional. If you specify BLDVRP, it applies to the entire CICS VR step.
  • Use the AMS LISTCAT command to determine the CI size of the data and index components of the VSAM data set or specify BLDVRP with no keywords to have CICS VR automatically calculate the LSR buffer space.
Attention: If you are going to specify the size and number of buffers in the BLDVRP command, familiarize yourself with the technique of specifying local shared resources before using the BLDVRP command in your CICS VR run; otherwise, you could inadvertently degrade performance. The more buffers you allocate, the greater the number of data and index control intervals that can be held in virtual storage. Over allocation can lead to severe paging on your system and can also increase the CPU time because of long buffer searches. With some investigation, you can find an optimal buffer size.

Examples

  BLDVRP B4K(50) B2K(200)

This BLDVRP command defines 50 buffers of 4K and 200 buffers of 2K in the VSAM resource pool.

Synonyms

The BLDVRP synonyms table provides the BLDVRP commands or keywords along with acceptable synonyms that can be used in place of the commands or keywords:

Table 1. BLDVRP synonyms
Command or keyword Synonyms
BLDVRP BVRP
B1K B1024
B2K B2048
B4K B4096
B8K B8192
B12K B12288
B16K B16384
B20K B20480
B24K B24576
B28K B28672
B32K B32768