I've looked over all the IBM-MAIN posts referring to AVGREC and don't see that anyone has ever brought this up before. I've read the relevant manuals, so I'm familiar with AVGREC syntax and how it's supposed to work. My concern is how to explain the differences in size allocation using BLKS/TRK/CYL allocation and what *should be* the AVGREC equivalent, according to the reference manuals (e.g. z/OS 2.4 MVS JCL Reference "AVGREC Parameter" http://ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.ieab600/xddavgr.htm ) The discrepancies are consistent across multiple z/OS systems at different sites, so I'm certain it is not site-specific. Case 1 - SPACE=(TRK,1),DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920) With these specs and a 3390 (emulated) Device Type, the file will hold *exactly* 698 records. These 698 records are then copied to a second file allocated using these specs: AVGREC=U,SPACE=(80,698),DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920),DISP=(,CATLG) But instead of occupying 1 track, the new file occupies 2 tracks. Why? Case 2 - SPACE=(TRK,1),DCB=(RECFM=F,LRECL=27920) Basically same as above - still 1 track - except now with only 2 records. And again, if these 2 records are copied to second file using AVGREC=U,SPACE=(27920,2),DCB=(RECFM=F,LRECL=27920),DISP=(,CATLG) the new file occupies 2 tracks instead of 1. Why? So far, I've run many test cases copying existing files to new files using AVGREC and in every case, when the existing allocation is completely full, the size allocated to the copy is *always* larger than what is necessary to accommodate the input file. In the case of a 100 cylinder input file, the excess allocation is over 13 cylinders! I have no explanation for this behavior, so I'm hoping someone here will.
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