Avoid Changed Default Values

August 3, 2005 Hey, Ted

After we upgraded to V5R3 from V5R2, the size of the logical files on our box appeared to have increased to 56 times their original size. The physical files had not grown any more than normal after day-to-day processing. After finally finding someone at IBM that knew something, we learned that IBM had changed the default value of the ACCPTH parameter of the Save Library (SAVLIB) command. This change caused the backups to take more space on the tape, leading us to believe that the size of the logical files had grown.

Under V5R2, the default value was ACCPTH(*NO). Under V5R3, the default is ACCPTH(*YES). I thought it strange that IBM had changed a default value, but the IBM’er at software support said it was a change the developers there had been after for a few years. Anyway, after changing the ACCPTH value in the backup program, the tapes went back to the original size. All’s well now. You might use that as a tip on the newsletter sometime, just so others will know.

Thanks for a great column.

–David

Thanks for the information, David. It’s strange to me that IBM would change a default value. I can’t remember the last time I saw IBM do that.

In the past, I have hard-coded a default value in a CL command, only because it occurred to me that any other value would prove disastrous. But to foresee every possible change that IBM might make is impossible, and to hard-code all parameter values is impractical.

To hard-code a default value when editing with SEU, prompt the command and key at least one character of the value in the parameter’s entry blank. Even though you key the character that is already there (in many cases, the first character is an asterisk), the prompter somehow recognizes that you keyed something and includes the parameter in the resulting command. The following Check Tape command explicitly specifies the default value *LEAVE in the ENDOPT parameter.

CHKTAP     DEV(TPA01) ENDOPT(*LEAVE)

–Ted