Socket addresses

A socket address in the AF_INET family comprises 4 fields: the name of the address family itself (AF_INET), a port, an IP address, and an 8-byte reserved field. In COBOL, a socket address looks like this:

01 NAME
    03 FAMILY      PIC 9(4) BINARY.
    03 PORT        PIC 9(4) BINARY.
    03 IP_ADDRESS  PIC 9(8) BINARY.
    03 RESERVED    PIC X(8).

You will find this structure in every call that addresses another TCP/IP host.

In this structure, FAMILY is a half-word that defines which addressing family is being used. In CICS®, IMS™, FAMILY is always set to a value of 2, which specifies the AF_INET IP address family. ¹ The PORT field identifies the application port number; it must be specified in network byte order. The IP_ADDRESS field is the IP address of the network interface used by the application. It also must be specified in network byte order. The RESERVED field should be set to all zeros.