Why do we code BLKSIZE=0 in JCL
Fri, 07/22/2011 - 07:24
At our mainframe shop, there are many jcl's which use BLKSIZE=0 for the datasets which are cataloged by the JCL.
From what I learnt during my training the BLKSIZE has to be a multiple of and would mean the number of logical records to be clubbed in a physical record to make one block of I/O
But if we use BLKSIZE of zero, will this mean that the file is not blocked or the system would block the file on its own?
Sat, 07/23/2011 - 19:27#1
an optimal blocksize exists for each different logical record length, and the type of device/disk the file is being stored on. Since the event of system managed storage, where the person/job allocating the file does not know or care what type of device/disk the file is going to be allocated too, it is best to let the system determine the optimal BLKSIZE. This is achieved by stating a BLKSIZE=0.