-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Frank Swarbrick Sent: Thursday, May 14, 2009 7:03 PM To: [email protected] Subject: BLOCK CONTAINS
I have been a bit of experimenting with z/OS QSAM files from a Cobol program and I find that the manuals don't exactly agree with my results. The manuals seem to imply that if you use the BLOCK CONTAINS clause (whether 0 or something else) then the file has a RECFM of either VB or FB. And if you don't include it then it's either V or B. <SNIPPAGE> Welcome to the MVS world. In the MVS world, we are not device dependant, nor are we data definition locked/blocked. We generally don't have to recompile our programs, change the DTF contents (DCB in MVS), etc. just because the file attributes change (xSAM to VSAM is the exception). We do not have to link PIOCS or LIOCS routines to our programs to handle I/O. The access method itself handles these things (particularly at the QSAM level). If you are using a vendor to help you migrate, you should spend a bit of time with them discussing all the changes to the environment and different concepts between VSE and MVS. As you have seen with your experiments, the information on the DD statement will override what you have in your program. And the label from the file in MVS actually contains the LRECL, BLKSIZE and RECFM, which as I recall, is not the case with VSE (for disk or tape). However, what happens if the DD statement only contains the UNIT, SPACE, DISP, and DSN? Does what you specify in the COBOL program then behave the way the manual says? Your ESDS files being taken to SAM: Just make sure that you don't actually depend on VSAM functions. And as far as your ASSIGN clause on the SELECT: you can probably leave them as they are -- but I haven't used the latest COBOL for a migration. In fact it has been a few years since I've done a migration. So unless it is going to enforce something, as I recall, only what is after the last "-" is paid attention to. And if you end with -SYS112 (or some such), then the DD being looked for is SYS112. Regards, Steve Thompson -- Opinions expressed by this poster may not reflect those of poster's employer. -- ---------------------------------------------------------------------- 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
