Multinode persistent session support allows an alternate application, on a different VTAM® node, to take over an application that is in a "SNPS recovery pending" state (entered when CLOSE ACB is issued or the application abends while in the enabled MNPS state). If OPEN ACB is issued in this state, VTAM will proceed as normal until the point where VTAM as about to initiate recovery.

At that time, the takeover VTAM will signal the current owning VTAM, informing it that the application wants to move. The owning VTAM will prevent any further updates to the application data in the coupling facility from the original application program, and will prevent any new data from flowing across RTP pipes associated with the application. The current owner then replies to the takeover VTAM, and initiates a non-persistent CLOSE ACB operation for the original application program (as if the PSTIMER had expired) to clean up awareness of the application at the original owner.

When the reply signal arrives at the takeover owner, an OPEN ACB response is returned to the application program, and recovery continues as in the case of a node failure.

If, for some reason, the MNPS takeover request was rejected by the current owning VTAM, the recovery OPEN ACB would be failed with an OPEN error code of X'58'. The recovering application does not need to reestablish persistence (SETLOGON OPTCD=PERSIST). If the application program opens an ACB for which persistence had been previously enabled, persistence remains enabled; however, the application can issue the SETLOGON OPTCD=PERSIST to ensure that the correct setting for the FORCETKO PARMS operand is in effect.

VTAM treats failure of an MNPS-capable application in the same manner as described for SNPS applications (see Application program recovery with single-node persistence enabled), with the addition of changing the state of application in the coupling facility to SNPS recovery pending. If the application reopens its ACB on the same VTAM, processing would again be identical to the processing of VTAM for SNPS applications, with the addition of changing the coupling facility state back to enabled.