The anchor configuration data set is the TCPIP.DATA data set. This is the base resolver configuration data set with information on host name, domain origin, and so on. It holds the TCPIPJOBNAME statement, which identifies the TCP/IP stack to use, and the DATASETPREFIX statement, which is used by the resolver code and other services when allocating configuration data sets. For more information on these data sets, see Configuration files for TCP/IP applications.
The key to selecting both a specific stack and resolver configuration data sets is to control which TCPIP.DATA data set a standard server or client address space allocates. Applications that use the z/OS® UNIX API can use Common INET to determine which stack an application will use. But, it is important to ensure that the search order and the contents of the resolver configuration data set are understood.
Native MVS™ servers and clients search for TCPIP.DATA in sequences as described in Search orders used in the native MVS environment.
z/OS UNIX servers and clients will search for TCPIP.DATA in sequences as described in Search orders used in the z/OS UNIX environment.