This segment resides below or above 16 megabytes depending on the
UCB location that you specify for the HCD device definition. You can
obtain its address with the following services:
- IOSCMXA
- IOSCMXR
- UCBLOOK UCBCXPTR
- UCBSCAN UCBCXPTR
Use the UCBCMEXT DSECT of the IEFUCBOB mapping macro to map the
UCB common extension.