You specify link security on the CONNECTION or SESSIONS resource
definitions. If you require more information about either of these
resources, see CONNECTION resources and SESSIONS resources.
Procedure
To specify that all sessions of a connection should have
the same link userid, specify the SECURITYNAME attribute of the CONNECTION
resource definition. If you do not specify a value for this attribute, CICS® uses
the default user ID.
To specify different link userids for individual groups
of sessions within a connection, specify the USERID attribute of the
SESSIONS resource definition. For each group of sessions, the value
specified overrides the SECURITYNAME attribute of the CONNECTION definition.