bdfd1m1pDatabase Administration

Using New Pool Blocks for Overflow Blocks

The following scenario addresses using new pool blocks for overflow blocks.

Problem

The pack operation can require heavy processing of LRECs between 1 pool block and another. This can be a problem for a file with high integrity requirements if the system fails during the pack operation.

Solution

When packing a subfile, the TPFDF product normally uses the same block chain as the subfile. It releases any pool blocks that it no longer needs.

Set the option in the DSECT (&SW00OP2,#BIT1) to tell the TPFDF product to use new pool blocks for the new compressed chain of overflow blocks.

As the last activity in the pack operation, the TPFDF product updates the prime block's forward chain pointer to the new chain reference. If the pack operation fails, the pointer will still point to the old chain.

Note:
This has potential implications for virtual file assist (VFA) performance. The new addresses need new slots in VFA, which will reduce its effectiveness. Because new pool storage is used every time a file is packed, be sure to allocate enough pool storage. You should also run PDU and RECOUP frequently.

DSECT Set Symbols

      &SW00OP2  SETC   '.1......'

DBDEF Statements

No changes are necessary if the changes are made in the DSECT macro.

Application Coding

Not applicable.