Skip to Content


Custom Search

Why do we code BLKSIZE=0 in JCL

2 replies [Last post]


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?
Sponsored Listing
Joined: 07/07/2011
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.
hi alan, then there is no

hi alan,

then there is no mistake in giving BLKSIZE=0....

Click the +1 button  below to share it with your friends and colleagues


Share this if you liked it!




Number of Registered users 561
Theme by Dr. Radut.