SIOCSAPPLDATA IOCTL

The SIOCSAPPLDATA ioctl enables applications to associate 40 bytes of application-specific information with TCP sockets they own. This information can assist problem determination, capacity planning, and accounting applications. This ioctl supports both 31-bit and 64-bit addressing modes.

This application-specific information, which is referred to as ApplData, is available from the following sources:

In the Netstat ALL/-A, ALLConn/-a, and COnn/-c reports where it can be searched using the APPLD/-G filter. See z/OS Communications Server: IP System Administrator's Commands for additional information on using ApplData information with Netstat.
In the SMF 119 TCP connection termination record. See Type 119 SMF records for additional information.
Through the callable TCP/IP network management interface. See TCP/IP callable NMI (EZBNMIFR) for more information.

The SIOCSAPPLDATA IOCTL constant and data structures for assembler applications are defined in the EZBYAPPL macro in the SEZANMAC data set, and for C/C++ applications they are defined in the EZBYAPLC header file in the SEZANMAC data set and the /usr/include file system directory.

Consider the following guidelines when using this ioctl:

The application is responsible for documenting the content, format, and meaning of the ApplData strings that it might associate with sockets it owns.
The application should uniquely identify itself with printable EBCDIC characters at the beginning of the string. Strings beginning with 3-character IBM® product identifiers, such as TCP/IP's EZA or EZB, are reserved for IBM use. IBM product identifiers begin with a letter in the range A – I.
You should use printable EBCDIC characters for the entire string to enable searching with Netstat filters.