Structure size for forward recovery log usage

You can merge the forward recovery logs written by many CICS® regions onto the same log stream. You can also use the same log stream for forward recovery data for multiple data sets.

You can calculate a value for number of entries for the INITSIZE and SIZE attributes in the following way: 
no. entries = writespersec * 12.5
where: 
writespersec = lesser of 25 or (N1 + ... + Nn)

where N1 .... Nn is the number of transactions per second writing to each data set.

You can calculate AVGBUFSIZE in the following way: 
AVGBUFSIZE = (bytespersec / writespersec) + 36
where:
  • bytespersec = (N1 * Wr1 * (D1 + rechdr) +.. (Nn * Wrn * (Dn + rechdr)))
  • writespersec = lesser of 25 or (N1 + ... + Nn), where:
    • N1 .... Nn is the number of transactions per second writing to each data set.
    • Wr1 ... Wrn is the number of write requests per transaction.
    • D1 .... Dn is the average record length for each data set.
  • rechdr is the record header length of each record.

If the records are WRITE ADD, WRITE ADD COMPLETE, or WRITE ADD DELETE records, rechdr is 84 and is followed by the record key and the record data (including its key).

If the result of the calculation shows a value for AVGBUFSIZE that is greater than the value defined for MAXBUFSIZE, the value defined for MAXBUFSIZE is taken as the value for AVGBUFSIZE, and writespersec is calculated: 
writespersec = bytespersec / (MAXBUFSIZE - 36)