Using the routing server connect exit

A routing server must provide the name of an exit routine on the SRV_MGR_EXIT@ parameter of IWM4CON when it connects to workload management. The exit is invoked when workload management needs to inform the server to terminate during quiesce or refresh processing. When the exit routine is invoked, register 1 contains the address of a parameter list mapped by the list form of the IWMSCXIT macro instruction. The parameter list includes an indicator of the action the exit is to take and the connect token associated with the IWM4CON macro issued previously by the server.

The execute and standard form of IWMSCXIT are intended for use only by the operating system.

Exit routine environment

The server connect exit routine receives control in the following environment:

Authorization

Supervisor state key 0

Dispatchable unit mode

SRB

Cross-memory mode

PASN=HASN=SASN with the current home address space the same as when the server issued the IWM4CON macro instruction.

AMODE

31-bit

ASC mode

Primary

Interrupt status

Enabled for I/O and external interrupts

Locks

No locks held

Serialization

It is possible for the exit to be called before the caller has received control back from IWM4CON. The exit or any program it drives (synchronously or asynchronously) must synchronize with the program issuing IWM4CON to ensure that IWM4CON has returned a connect token prior to issuing IWM4DIS (disconnect) or any other service that requires the connect token.

Location

The server exit must be a resident routine callable from the server address space and must remain available after the server manager disconnects or after the termination of the server task which issued the IWM4CON. The exit need not persist after termination of the server address space.

The input parameter list is in pageable storage addressable in the primary address space, but should not be changed by the exit.

Exit Recovery

The system may cause the server to become ineligible to be recommended by IWMSRFSV (find server) if there have been repetitive errors in calling the exit. The exit may optionally establish a functional recovery routine (FRR) or ESTAEX for any needed recovery or cleanup of its resources.

Register usage

Upon entry to the exit, the register contents are as follows:

0: Not defined
1: Address of the input parameter list
2-13: Not defined
14: Return address
15: Entry point address

Upon entry to the exit, the access register contents are undefined.

Upon return from the exit, the register contents are expected to be:

0: Reason code, if GR15 return code is non-zero
1-14: Not defined (need not be restored to value on entry)
15: Return code

Upon return from the exit, the access register contents are unchanged.

Example

The following example shows how to invoke the IWMSCXIT macro instruction and the resulting parameter list mapping. This is the parameter passed to the routing server exit routine specified on the SRV_MGR_EXIT@ parameter of IWM4CON.

          IWMSCXIT MF=(L,MYSCXITPL)

+MYSCXITPL DS   0D                 ++ IWMSCXIT PARAMETER LIST
+MYSCXITPL_XVERSION DS XL1         ++ INPUT
+MYSCXITPL_XRSV0001 DS CL1         ++ RESERVED
+MYSCXITPL_XPLISTLEN DS XL2        ++ INPUT
+MYSCXITPL_XACTION DS BL.8         ++ ACTION INDICATORS
+MYSCXITPL_XACTION_QUIESCE EQU B'10000000'
+                                  ++ INDICATES QUIESCE ACTION
+MYSCXITPL_XACTION_RESUME EQU B'01000000'
+                                  ++ RESUME
+MYSCXITPL_XRSV0005 DS CL3         ++ RESERVED
+MYSCXITPL_XCONNTKN DS BL.32       ++ CONNECT TOKEN FROM IWM4CON
+MYSCXITPL_XRSV000C DS CL4         ++ RESERVED
+MYSCXITPLL EQU *-MYSCXITPL        ++ LENGTH OF PARAMETER LIST