http://publib.boulder.ibm.com/infocenter/zos/v1r12/index.jsp?topic=%2Fcom.ibm.zos.r12.idad400%2Fblksz.htm
Use BLKSIZE=0. It will use the optimum (largest) blocksize that is valid. 32K, 64K, or 256K. On Wed, Aug 21, 2013 at 10:53 AM, Skip Robinson <[email protected]> wrote: > We're having ongoing 'discussions' with our tape vendor over through-put > performance. Vendor is suggesting that we should be using modern man-size > blocks like 256K. I did some simple testing yesterday to satisfy myself > that--whatever it might take to super-size our tape file blocks--simply > adding > > BLKSIZE=some-large-number > > to a DD card will not cause the creation of very large blocks. After > running such a job with an existing RYO program, the resulting BLKSIZE was > in fact 32K. No error messages, just no big blocks. > > Am I right in asserting that, whatever benefit we might derive from > uber-blocks, we cannot get there by fiddling with JCL? > -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
