Rollover has been around for a while. I have some "GDG wrap" tests from 2007. At that time, GDGs defined in late 1979 with a new generation created each day would have been be reaching G9999.
Bob Longabaugh CA Technologies Storage Management -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of John Eells Sent: Friday, May 27, 2016 5:58 AM To: [email protected] Subject: Re: Proper way to resolve existing GDG GnnnVnnn by relative reference Lizette Koehler wrote: > Barry, > > I have heard that the number of GDGs may be allowed to go beyond 255 > generations. Do you have any insight on this? I am wondering how this > enhancement may impact the GDG Wrap condition. > <snip> GDGEs were introduced with z/OS V2.2 and can have up to 999 generations.* I believe both GDGs and GDGEs both "roll over" from G9999V00 to G0000V00 these days without needing to be redefined, but I don't recall when we did that (other than it wasn't recently). The number of concurrent generations is something you choose when you define either one. * We were going for an even thousand until we weighed the value of "one more generation" against the cost of updating a bazillion messages to add space for another digit and decided 999 was close enough! -- John Eells IBM Poughkeepsie [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
