Anton, For non-SMS, if you open and write to the dataset it can extend to up to 59 volumes. The unit count is not persistent across job and job steps, so once you close it you are stuck with the number of volumes you had at close. If you allocate the file without opening it (eg IEFBR14) then you get just one volume.
As long as I can remember allocations to STORAGE and PUBLIC volumes have always worked this way. Only Private Volumes required the Volume Parameter - but my experience starts with XA. For SMS managed datasets without guaranteed space, and a Unit count of 59 in the data class, the dataset is allocated with 58 candidate volumes, so later updates can extend to volumes beyond those used at last close. This is good for DISP=MOD and IEFBR14 allocations. For SMS managed and Guaranteed Space=YES, the dataset will be allocated with a primary extent on all 59 volumes at allocation. This was an old trick for creating multi-volume SAS datasets in earlier versions of SAS. This happens with Unit Count in the JCL or the DATACLAS Products like ACC/SRS or SMS Space Recovery rules can change this behavior. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Anton Britz > Sent: Friday, August 08, 2008 12:16 PM > To: [email protected] > Subject: [IBM-MAIN] zOs 1.7 storage pack allocations > > Question : > > Would the following JCL allocation automatically use more than one > storage > pack on zOS 1.7 ? > > //DDEXPA1 DD DSN=SYS3.UCDCP.ADASEL, > > // DISP=(NEW,CATLG,DELETE), > > // UNIT=(3390,59), > > // SPACE=(CYL,(1000,1000),RLSE), > > // DCB=(LRECL=27994,RECFM=VB,BLKSIZE=0) > > Note: In the old days, MVS picked one Storage pack and it never > extended > the secondary allocation to another pack without the Volume parameter. > Maybe things changed now because the Operating system release numbers > are > increasing ? > > Anton > > ---------------------------------------------------------------------- > 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
