On Wednesday, 06/01/2011 at 10:50 EDT, Sergio Lima <sergiovm...@hotmail.com> wrote:
> We want write a REXX EXEC , that do a Update in place. > Another words, I need, read the record 1 from the file, and then rewrite the > same record. > Is possible? Yes. There are a few programming considerations: 1. If the file is RECFM F, you can change any record you want. 2. If the file is RECFM V, you can change any record you want. 3. If you change the LRECL of a record in a RECFM V file, that record will become the last record in the file. 4. If other virtual machines have the disk accessed while you're doing this, then you can use filemode number 6 to cause the records to be physically rewritten to the same disk location. 5. Update-in-place using fm6 exposes the file to corruption if the system or CMS dies in the middle of a write. For more information, please read these (sub)sections of Ch. 9 (CMS File System) of the CMS Application Development Guide for Assembler - Replacing Records - EDF Data Integrity - Extending the file Alan Altmark z/VM and Linux on System z Consultant IBM System Lab Services and Training ibm.com/systems/services/labservices office: 607.429.3323 mobile; 607.321.7556 alan_altm...@us.ibm.com IBM Endicott
