Introducing TCP/IP concepts: Socket libraries

Figure 1 illustrates the TCP/IP networking API relationship on z/OS®.

Figure 1. TCP/IP networking API relationship on z/OS

Diagram that shows the relationship between different TCP/IP networking API in the z/OS environment.

When we create a sockets program, we use something that generally is called a sockets library. A sockets library consists of both compile-time structures, statically linked support modules, and run-time support modules.

There are two main sockets execution environments in z/OS with available libraries:

Native TCP/IP (implemented by TCP/IP in z/OS Communications Server)
UNIX (implemented by z/OS UNIX System Services [Language Environment])