Hi List, John McKown's response to Ron's S013-64 issue interested me. I had not realized that SMS automatically wrote an EOF to newly-allocated datasets.
John pointed me to http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2i650/8.1 which states "For sequential data sets, SMS writes a hardware EOF at the beginning of the data set at initial allocation. This prevents data integrity problems when applications try to read the data before data is written in the data set." Just for fun, I allocated four new datasets using IEFBR14: > DSORG=PS SMS-managed > NO DSORG SMS-managed (had to modify my DC ACS routine to get this) > DSORG=PS non-SMS > NO DSORG non-SMS All utility programs (e.g. IBMGENER, IDCAMS, IEHLIST and IEBPTPCH) referencing any of these datasets via any input DD (e.g. SYSIN or SYSUT1) recognized that there was no data. I wonder, therefore, whether newly-allocated datasets are now getting initialized with an "EOF". Seems unlikely to me that all are because all JCL references up to and including V1R12 have a note for DISP=NEW (Note: Initialize a new data set to ensure that it is empty). I don't know of a tool that we have at this organization which indicates the presence of an "EOF" (count with keylen=0 and datalen=0) in a track. Would any of you have such a utility and be willing to use it to test the results of IEFBR14-allocating the aforementioned datasets? I'm curious to know whether newly-allocated datasets are "empty" (no content) or "null" (hardware EOF at the beginning). I found a definition of "empty" versus "null" in the final paragraphs of "DFSMSdfp Storage Administration: Chapter 7. Defining data classes - Planning data classes" Thanks, Alan ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
