In HDAM, HIDAM, PHDAM, and PHIDAM databases, you can allocate
free space when your database is initially loaded.
Free space can only be allocated for an HD VSAM ESDS
or OSAM data set. Do not confuse the free space discussed here with
the free space you can allocate for a VSAM KSDS using the DEFINE
CLUSTER command.
To calculate the total number of
CIs or blocks you need to allocate in the database, you can use the
following formula:
A = B x (fbff / (fbff - 1)) x (100 / (100 - fspf))
Where
the values are:
- A
- The total number of CIs or blocks needed including free space.
- B
- The number of blocks or CIs in your database.
- fbff
- How often you are leaving a block or CI in the database empty for free space.
-
For an HDAM or HIDAM database, this is the fbff value that is specified on the
FRSPC= parameter of the DBD.
For a PHDAM or PHIDAM database, this is the value that is specified either on the FBFF= parameter
of the INIT.PART or CHANGE.PART DBRC command or in the Free block freq. factor
field of the Partition Default Information panel of the HALDB Partition Definition utility
(%DFSHALDB).
If you are using DDL, this is the value that is specified on the FREEBLOCK parameter of the
CREATE or ALTER TABLESPACE statement.
- fspf
- The minimum percentage of each block or CI you are leaving as free space.
-
For an HDAM or HIDAM database, this is the fspf value that is specified on the
FRSPC= parameter of the DBD.
For a PHDAM or PHIDAM database, this is the value that is specified either on the FSPF= parameter
of the INIT.PART or CHANGE.PART DBRC command or in the Free space percentage field
of the Partition Default Information panel of the HALDB Partition Definition utility (%DFSHALDB).
If you are using DDL, this is the value that is specified on the FREESPACE parameter of the
CREATE or ALTER TABLESPACE statement.