On 6/5/2013 10:12 AM, Paul Gilmartin wrote:
<RHETORIC> How, then, do OSes with native FBA filesystems manage to support appending to files?</RHETORIC> Couldn't QSAM have been designed to to likewise?
Either they fill every block, or they keep a pointer. When xSAM was designed, every byte was precious, and most control blocks kept only a TTR rather than a complete offset. When Checkpoint/Restart became available, it had the same problem.
It is still possible to add extra code to OPEN MOD to read the last block, and adjust the buffers, but there is no business case for it. Whenever direct addressing was convenient, I used BSAM or BDAM, and handled MOD and short buffers with my own code. With VSAM the issue disappeared.
Gerhard Postpischil Bradford, Vermont ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
