You can enable SSCPs to take over cross-domain resources without requiring intermediate SSCPs to issue a MODIFY CDRM command. This enables VTAM® to automatically change the CDRM ownership of a CDRSC. This can be useful in cross-network sessions where one of the session partners has been taken over by a different SSCP and an attempt is made to establish a new session.

This SSCP takeover of cross-domain resources is accomplished in the definition of the CDRSC with the VFYOWNER operand. VFYOWNER=YES can be specified only for a CDRSC that is coded with the NETID and CDRM operands. Specifying VFYOWNER=NO (which is the default) allows VTAM to automatically change the CDRM ownership of a CDRSC. VFYOWNER=YES in the CDRSC definition makes VTAM reject session setup requests that contain a conflicting owner. The default (VFYOWNER=NO) allows the takeover of a CDRSC without the need for intermediate SSCPs to issue a MODIFY CDRM command.

The MODIFY CDRM command does not need to be used for dynamically defined CDRSCs. If a session setup request is received for a dynamically defined CDRSC from a CDRM other than the current CDRM owner, VTAM automatically changes the CDRM ownership of the CDRSC. However, the operator might still want to use the MODIFY CDRM command if LU-LU session recovery is initiated by the logical unit that received the original session request.

For example, a terminal user logs on to an application program, and the CDRSC representing the terminal is defined dynamically in the domain of the application program. If the session between the application program and the terminal is disrupted, the application program might try to reinitiate the session instead of requiring the terminal user to log on again. In this case, the VTAM operator in the domain of the application program needs to use the MODIFY CDRM command to change the CDRM owner of the CDRSC representing the terminal, if the terminal is taken over by a backup SSCP other than the SSCP in the application program domain.

A VTAM domain that takes over a cross-domain resource does not need to use the MODIFY CDRM command because in this case, the VTAM shadow resource function applies. For more information about shadow resources, see Shadow resources.