Most of the Performance on tape drives can be accomplished by matching the BUFNO= parameter to the Devices I/O Data Transfer Size. For your model that's probably (most Tapes and VTS are) a 128kb size, so you would want enough buffering to hold at least 1 128k Large Block.
So for a BLKSIZE=32768 file you would want a BUFNO=4 at minimum, but would be better off with BUFNO=16 or BUFNO=32 (4 or 8 Large Blocks) as Some VTS Units and the 256 track 3590E have a 256kb Transfer Size. However DFSORT ignores any buffering (It has its own I/O context) on both DASD and TAPE so no need to use it when doing sorts. The other thing you can do is to add a step at start of job that will Pre-Mount the tapes and then Retain them for any following steps, using IEFBR14 as a stub program, and the VOL=(,RETAIN) option mentioned earlier. There is also the /*setup card that can be used on some JES systems. Darren -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Kenaan Tabikh Sent: Wednesday, February 13, 2008 11:03 AM To: [email protected] Subject: 3590 stacking performance via JCL? Is anyone aware of a JCL parameter that enhances 3590 tape stacking performance? Maybe something in DATACLAS? I was told about this but cannot find anything. Maybe DCB=OPTCD=? Thanks, Ken Tabikh Verizon Data Services ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
