Getting CA-7.920 I/O ERROR ON SCRATCH QUEUE when starting CA 7 r12 with CKPT type start (first time).
DAIO statement in the initialization file had DASD=3390. There can be 33 1024 byte blocks written to a 3390 track. In the dump, the I/O error was produced when trying to write the 32nd block. If VIO is genned as 3380 then only put 31 1024 byte blocks on can be written on a track.
Change the DAIO statement to be DASD=3380 or gen 3390's for VIO or make the scratch and DQT queues hard coded data sets instead of VIO in the CA7ONL procedure.