The DFHDSSRM waits are summarized here. All but PSUNBECB are posted by DFHZGRP.
Module Type Resource_name Resource_type ECB
DFHSII1 MVS ZGRPECB AP_INIT TCTV_ZGRP_FIN_ECB
DFHZGUB OLDC PSUNBECB ZC_ZGUB WAIT_RPL_ECB
DFHZGRP MVS PSOP1ECB ZC_ZGRP OPNDST_ECB
DFHZGRP MVS PSOP2ECB ZC_ZGRP OPNDST_ECB
DFHZGRP MVS PSINQECB ZC_ZGRP INQUIRE_ECB
DFHZGRP OLDC TCTVCECB ZC_ZGRP TCTVCECB
where the waits are issued for the following reasons: