CICS® TCP/IP supports the AF_INET and AF_INET6 TCP/IP addressing family (or domain, as it is called in the UNIX system). This is the Internet domain, denoted by AF_INET or AF_INET6 in C. Many of the socket calls require you to define the domain as one of their parameters.

A socket address is defined by the IP address of the socket and the port number allocated to the socket.