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

.-----------------------------------.
V |
>>-BLDVRP----+-------------------------------+-+---------------><
+-B512--(--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
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 synonymsCommand 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 |