Using the GETDSAB macro to find the UCB address

This procedure can be used by application programs that are the only task running in an address space, for either non-concatenated DD statements or data sets that reside on a single volume.

To find the UCB address for a DD name without an Open DCB, you can provide a DD name, an open DCB or ACB or a known data set association block (DSAB) address or request the first DSAB address. From this address, calculate the address of the associated TIOT entry, and the corresponding UCB address.