On Fri, 2012-05-11 at 11:43 -0400, Shmuel Metz (Seymour J.) wrote: > In <[email protected]>, on > 05/10/2012 > at 08:12 PM, "Donnelly, John" <[email protected]> said: > > >Is there any way to create or pretend to create a GDG base greater > >than 255... > > No. Has anybody submitted a requirement for that? It should be doable, > but there would have to be a sound business case for it; it wouldn't > be trivial.
I thought about this a bit during the afternoon, and based on what I remember of ICF catalog structure for GDGs, this would be a bear. (What I remember is over 20 years old, so take this with 20 years worth of NaCl.) A GDG's catalog information is entirely kept within a single GDG "sphere record", so long as all the data will fit within your catalog's LRECL. If the sphere record would exceed the LRECL, then extension records are created, one at a time per GDS. The key for nonvsam entries (including GDG sphere records) is 45 bytes long - base name followed by a binary zero. GDG extension records are keyed by base name and one-byte binary integers starting at X'01'. It follows that you cannot have more than 254 extension records. So expanding the max number of generations much past 255 is problematic with the current key design. I guess IBM could walk in a new catalog format (by e.g. allowing more than one GDS per extension record), but I wouldn't look forward to all the coexistence woe that might provoke. -- David Andrews A. Duda & Sons, Inc. [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
