A socket is a method of communication between two processes that allows communication in two directions, in contrast to pipes, which allow communication in one direction. The processes using a socket can be on the same system or on different systems in the same network. A program creates a socket with the socket() function.

When setting up for sockets, your two choices are INET and CINET (Common INET). These are network sockets, and this topic describes those sockets in detail. Local network sockets (AF_UNIX), which do not have network connectivity, are also available, but are not discussed. INET and CINET are file systems that are in the AF_INET and AF_INET6 family of sockets. This topic helps you decide which file system is best for you to use and describes how to set it up. It contains examples that are based on an assumed sample configuration. You will need to modify the examples based on the requirements for your installation.

User-written socket applications can use TCP/IP as a communication vehicle. TCP/IP is also the transport provider when users rlogin or telnet from a UNIX workstation directly into the z/OS shell.

You can use CINET configured with just one stack, but this configuration will not run as efficiently as INET. Choosing between INET or CINET provides background information that you may need.