Auxiliary storage requirements for an MSDB

DASD space is needed to keep image copies of MSDBs when they are dumped at system and shutdown checkpoints. The data sets involved are the MSDBCP1 and MSDBCP2 data sets.

The same calculations apply to the MSDBDUMP data set, which contains a copy of the MSDBs following a /DBDUMP DATABASE MSDB command.

The data sets just discussed are written in 2K-byte blocks. Because only the first extent is used, the allocation of space must be on cylinder boundaries and be contiguous.

Space allocation is calculated like this:

SPACE=(2048,(R),,CONTIG,ROUND)

The calculation of the number of records (R) to be allocated can be derived from the formula:

(E + P + 2047)/2048

      where:

      E = main storage required, in bytes, for the Fast Path extension of the
           CNTs (ECNTs)

      P = main storage required for all MSDBs as defined by
           the PROCLIB member DBFMSDBx

E is determined by the following formula:

E = (20 + 4D)T

      where:

      D = number of MSDBs using logical terminal names as keys

      T = total number of logical terminal names defined
          in the system