The XRF takeover process involves several operations. Before each operation can be started, one or more events must have completed. For example:
A system task that issued a takeover request to CAVM waits on the ECB WCSTCECB in the CAVM static control block (DFHWCGPS) until CAVM has decided to accept or reject the request. The DFHKC TYPE=WAIT and DCI=SINGLE requests are issued in DFHWSRTR. The CAVM TCB posts WCSTCECB in either DFHWSTKV (the normal case) or DFHWSSOF (CAVM failure).
The following ECBs each represent an event. The ECBs are located in the static storage for DFHXRP. The ECBs and the events are:
This ECB is posted by DFHXRA, following a successful call to the CAVM to initiate takeover. Once the ECB has been posted, DFHXRA attaches a system transaction to initiate the switch of terminals with backup sessions. DFHXRA is called from either the surveillance task (DFHXRSP), or the console communication task (DFHXRCP). No tasks wait for XRSTIECB to be posted.
The XRSIAEB ECB is posted by DFHXRA, following notification by the CAVM that an alternate system is now the incipient active system. DFHXRA is called from the surveillance task (DFHXRSP). No tasks wait for XRSIAECB to be posted.
The XRSTCECB ECB is posted by DFHXRA, following notification by the CAVM that an active system has terminated. There can be a delay in posting the ECB if:
DFHXRA is called from the surveillance task (DFHXRSP). Only one task, the system initialization task (DFHSII1), waits for XRSTCECB to be posted. When the ECB is posted, DFHSII1 opens the restart data set, for DFHRC use as well as for DFHCC use, and then calls DFHXRA to post the XRSRAECB.
The XRSRAECB ECB is posted by DFHXRA once the restart data set has been opened, for DFHRC use as well as for DFHCC use. DFHXRA is called from the system initialization task (DFHSII1). Two tasks wait for XRSRAECB to be posted:
The XRSSSECB ECB is posted by DFHXRA following notification by the CAVM that the time-of-day clock is synchronized with active sign off. DFHXRA is called from the surveillance task (DFHXRSP). No tasks wait for XRSSSECB to be posted.
The XRSSTECB ECB is posted by DFHXRA, following notification by the CAVM that the time-of-day clock is synchronized with respect to active system termination. There may be a delay in posting the ECB if the time indicated by the active system time-of-day clock is significantly ahead of that indicated by the alternate system time-of-day clock. DFHXRA is called from the surveillance task (DFHXRSP).
Only the system initialization task, DFHSII1, waits for XRSSTECB to be posted.
You are only likely to find either of the CICS-supplied transactions CEDA or CESN waiting on a resource type of XRPUTMSG, and only during XRF takeover by the alternate CICS system. It can indicate either of these conditions:
If it seems clear that MVS RESERVE locking is not implicated, refer the problem to the IBM® Support Center.