With PDSE and SMS compressed data sets, there is the concept of a logical blocksize and a physical blocksize. In both cases, the physical blocksize is 4096. That is the blocking factor used to store the data on disk. The logical blocksize, either specified by the user or selected by System Determined Blocksize, is used to determine the size of the buffers when the data set is opened. This is the blocksize you see when you look at the data set attributes in the VTOC.
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of George D Dranes Sent: Monday, October 02, 2006 7:47 PM To: [email protected] Subject: Default System BLKSIZE for PDSE I have a question I was hoping someone on the board would have some experience with. I'm converting many of our PDSs to PDSEs. Most of these datasets are LRECL=80 and RECFM=FB. The default blksize (which I typically take) for the PDS is 27920 while the default for the PDSE is 32720. I'm curious if its fine to take the default of 32720 even though its not using half track blocking like the PDS. Is it safe going with the default or am I wasting a bunch of space? Does it matter with PDSE's since they are radand written to differently? Thanks for all of your help. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
