All the options discussed in this section are alterable, except
for RECORDSIZE. If you decide your initial selection is inappropriate,
you can use the access method services ALTER command to change it.
- Buffers
- You can specify buffer size on three different parameters:
- BUFFERSPACE
- The required buffer space for your catalog is determined by catalog.
You only need to specify this if you want extra buffer space for your
catalog. In general, allow catalog to determine buffer space. The
number of buffers specified applies to each processor.
- BUFND
- Specifies the number of buffers for transmitting data between
virtual and auxiliary storage. The default, STRNO+1, is usually adequate.
When a catalog contains large GDGs or other spanned records, the number
should be increased accordingly to a minimum of MAXLRECL/CISIZE+STRNO.
- BUFNI
- Specifies the number of buffers for transmitting index entries
between virtual and auxiliary storage. The default, STRNO+2, is adequate
for 3 levels of index in the catalog. If the catalog index exceeds
3 levels of index, the minimum BUFNI equals the number of levels of
index - 1 + STRNO.
- FREESPACE
- The free space allows catalog updates without an excessive number
of control interval and control area splits.
The following parameter affects catalog performance but can only
be specified when the catalog is initially defined.
- RECORDSIZE
- The record size information is ignored when a catalog is defined.
It will always set the record size information for a catalog as though
RECORDSIZE(4086 32400) was specified. The maximum value should always
be the default if large records could be generated. Large catalog
records are generated for GDGs that have many GDSs. Master catalogs
with user catalog connector records that contain a large number of
aliases also have large catalog records.