Primary space allocation for Db2 table spaces and indexes

You can specify the primary space allocation or let Db2 use default values for primary space allocation of Db2-managed data sets.

If you specify a PRIQTY integer in CREATE TABLESPACE, ALTER TABLESPACE, CREATE INDEX, or ALTER INDEX statement, the actual primary quantity is at least integer KB.

If PRIQTY integer is not specified or PRIQTY -1 is specified, the actual primary quantity is determined as follows:
  • For table spaces, the default values are 1 cylinder (720 KB) for non-LOB table spaces and 10 cylinders for LOB table spaces, unless a non-zero value is specified for TSQTY subsystem parameter. If TSQTY is set to a non-zero value, the actual primary quantity is at least that value.
  • For indexes, the default value is 1 cylinder, unless a non-zero value is specified for IXQTY subsystem parameter. If IXQTY is set to a non-zero value, the actual primary quantity is at least that value.

To indicate that you want Db2 to use the default values for primary space allocation of table spaces and indexes, specify a value of 0 for the following parameters on installation panel DSNTIP7, as shown in the following table.

Table 1. DSNTIP7 parameter values for managing space allocations
Installation panel DSNTIP7 parameter Recommended value
TABLE SPACE ALLOCATION 0
INDEX SPACE ALLOCATION 0

Thereafter:

  • On CREATE TABLESPACE and CREATE INDEX statements, do not specify a value for the PRIQTY option.
  • On ALTER TABLESPACE and ALTER INDEX statements, specify a value of -1 for the PRIQTY option.

Primary space allocation quantities do not exceed DSSIZE or PIECESIZE clause values.

For those situations in which the default primary quantity value is not large enough, you can specify a larger value for the PRIQTY option when creating or altering table spaces and indexes. Db2 always uses a PRIQTY value if one is explicitly specified.

If you want to prevent Db2 from using the default value for primary space allocation of table spaces and indexes, specify a non-zero value for the TABLE SPACE ALLOCATION and INDEX SPACE ALLOCATION fields on installation panel DSNTIP7.