Tape Device Allocation
After the GO reply to a pre-mount message, and following the pre-mount processing, IBM® Connect:Direct® allocates a tape device using Defer mounting. If an allocation error occurs, and the allocation error code is in the ALLOC.CODES parameter of the IBM Connect:Direct initialization parameters, IBM Connect:Direct retries the operation.
When device allocation completes successfully, IBM Connect:Direct issues a z/OS-format Open mount message to allow tape management and visual display routines to process the request. The format of the message follows.
Following the IEC501A message, IBM Connect:Direct issues a WTOR to allow you to mount the tape or cancel the request.