Description:   This statement is required. It is used to specify configuration information used by the IMS™ Listener.

PORT= port

Port number that the Listener binds to for connection requests. Use an integer between 0 and 65535, inclusive.

MAXTRANS= maxtrans

The maximum number of TRANSACTION statements to be processed in the configuration file. Use an integer between 1 and 32767, inclusive.

MAXACTSKT= maxskt

The maximum number of sockets the Listener can have open awaiting an MPP TAKESOCKET at one time. This value is an integer from 1 to 2000, inclusive. The number includes the socket bound to the port through which it accepts incoming requests.

ADDRSPCPFX= prefix

One or two characters (consisting of the numbers 0–9, the letters A–Z, and the characters $, @, and #) used in generating unique identifiers for started IMS transactions.

BACKLOG= backlog

This parameter is optional and is used to specify the length of the backlog queue maintained in TCP/IP for connection requests that have not yet been assigned sockets by the Listener. Use an unsigned number from 1 to 32767 inclusive. The default value is 10.

Tip: The backlog value specified on the listen call cannot be larger than the value configured by the SOMAXCONN statement in the stack's TCPIP PROFILE (the default value is 10), no error is returned if a larger backlog is requested. If you want a larger backlog, update the SOMAXCONN statement. See the z/OS Communications Server: IP Configuration Reference for details.