Resource registration places information about the location of resources in a directory services database. This registration reduces broadcast searches by ensuring that a resource will be found in the directory services database. Resources can be registered to a directory database on a network node server or to a central directory server, or both. By registering resources to a network node server, you ensure that the resources will be found during a search. By registering resources to a central directory server, you ensure that the resources will be found without requiring a broadcast search.

Resources are registered by using the REGISTER operand on the APPL, CDRSC, LOCAL, and LU definition statements. This operand can also specify that a resource is not registered. The defaults for registration change depending on the type of resource and whether the resource is located on an end node or a network node. Table 1 shows the default registration values for resources.

Dynamic registration for a resource can be initiated while VTAM® is running by using the MODIFY RESOURCE command. For more information, see z/OS Communications Server: SNA Operation.

Because the characteristics of an independent LU and of the node on which it resides are not recorded by VTAM, it is difficult to determine the appropriate level of registration for all cases. Therefore, independent LUs are not registered by default.

VTAM end nodes register their dependent LUs with their network node server by default. This includes all resources defined by LOCAL definition statements and LU definitions with a nonzero LOCADDR value. A resource on a VTAM end node that is not registered to the network node server will not be found during a search unless that resource has initiated a request through the network node server. Registering all end node resources ensures that they will be located by a search. You can also specify that these resources be registered to a central directory server.

Applications are registered to a central directory server by default, with the exception of TSO applications. For more information about default registration of TSO applications, see Resource registration in an APPN network.

Resources on a network node can also be registered to a central directory server if one exists. By default, network nodes register only their applications to a central directory server.