On Mon, 29 Jun 2026 20:34:57 -0400, Joseph Reichman <[email protected]> wrote:
>Would anyone know how to get the net bytes per track for a 3390 (Sorry - TL;DR the other responses) From the book: "For all currently supported devices, DEVTYPE does not return enough information to perform space calculations. TRKCALC should be used to perform space calculations." 3390s report size information back to the host, including the maximum number of bytes that "user" records (R1 to Rn) can occupy, including all count fields, key fields, keys, gaps, sector markers, error detection, and whatever else might be on the track. The device also tells the host how to calculate how many bytes on a track are consumed by a record with a given key length and data length. That calculation leads you to conclude that you can store a maximum of 56,664 bytes of user data on a single track. The user data is from the 3390's perspective, so access method objects like the RDWs and BDWs must be accounted for in that 56,664. Regard, Alan Altmark IBM z/VM Development >I have been using devtype ddname,buffer,devtab > > >Where buffer is a 32 byte output field > >But it keeps on coming back with the overhead of 58,864 > >I think the net is 56,664 > >I would like to get that figure programmatically instead of hard coding it ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
