While SEP is certainly obsolete in the world of virtual disk, AFF is very much required in cases where many--perhaps dozens of--tape files are to be read in a single step. MVS does not know from virtual, so he wants to allocate 25 drives to read 25 tape volumes unless constrained by AFF. Although these drives may be virtual, any configuration has a finite number defined. 25 may exceed the total defined, or may exceed the number allocatable at execution time.
. . JO.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 626-302-7535 Office 323-715-0595 Mobile jo.skip.robin...@sce.com From: "Joel C. Ewing" <jcew...@acm.org> To: IBM-MAIN@LISTSERV.UA.EDU, Date: 08/30/2013 08:55 AM Subject: Re: UNIT=SEP still alive (?) Sent by: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On 08/30/2013 08:44 AM, Clark Morris wrote: > On 29 Aug 2013 20:39:00 -0700, in bit.listserv.ibm-main you wrote: > >> On Thu, Aug 29, 2013 at 6:25 PM, Clark Morris <cfmpub...@ns.sympatico.ca> wrote: >>> On 29 Aug 2013 14:33:21 -0700, in bit.listserv.ibm-main you wrote: >>> >>>> The z/OS V1R9 MVS JCL Reference--The 12th edition of 2007 September >>>> and the oldest one I have on my workstation--describes AFF, SEP, >>>> SPLIT, and SUBALLOC as "obsolete subparameters" on page 5-18. >>> >>> I can see SEP, SPLIT and SUBALLOC being obsolete but AFF still should >>> be useful in conserving device use for tape drives. For example >>> SORTIN and SORTOUT many times were allocated that way. >>> >> UNIT=REF=DATA.SET.NAME,LABEL=(2,SL) does work. > > While I don't have a JCL manual at home, > VOL=REF=data.set.name,LABEL=(n,SL) is the best way to put multiple > files on the same volume (for output > VOL=REF=*.stepname.procstepname.ddname works better). UNIT=AFF=ddname > is for putting things on different volumes using the same device. > > CLark Morris >> >>> Clark Morris >>>> >>>> John Gilmore, Ashland, MA 01721 - USA >>>> ... I don't see any "UNIT=REF=dsname" syntax in my JCL manual, only "UNIT=AFF=ddname" and VOL=REF=dsname. I also don't see the need for UNIT=AFF disappearing anytime soon. A highly counter-intuitive case for many new users used to be the case of a DDNAME with concatenated tape data sets, where the data sets are obviously constrained to access in sequential fashion; but the MVS default (without UNIT=AFF) was to allocate separate tape drives concurrently for each of the concatenated tape data sets, and then proceed to use them one at a time -- a highly antisocial act in environments with limited drives. Especially in the case of tape data sets, constraining the number of units via a dataset name reference rather than DD reference wouldn't make sense, since tape data set names aren't required to be cataloged and might not be unique even within the same job step! -- Joel C. Ewing, Bentonville, AR jcew...@acm.org ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
