Procedures

For any allocated data set:
  1. Invoke the GETDSAB macro, specifying the name of the desired DD. The system returns the pointer to the DSAB associated with the required TIOT entry. This procedure works only for allocations that did not use the XTIOT or UCB nocapture options of dynamic allocation.
  2. Use the IHADSAB macro to map the DSAB. Get the word in DSABTIOT. It is at offset 16. It is a pointer to the TIOT entry.
  3. Use the IEFTIOT1 macro to map the TIOT entry, which begins at TIOELNGH. The first UCB address is the 3-byte field at TIOEFSRT. It is at offset 17.
  4. Issue the RESERVE macro, specifying the address obtained in step 3 as the parameter of the UCB keyword. Do not code the LOC=ANY option because this UCB address is 24-bit.
Parent topic: Using the GETDSAB macro to find the UCB address