icm/max_conn 

This parameter determines the maximum number of (simultaneous) open connections in the ICM or in the SAP Web dispatcher.
The parameter value can be greater than icm/max_threads, as inactive connections require no thread in the ICM.

Value Range	Unit	Default Setting
10 - 32000	Integer	300

Requirements

The maximum number of sockets that one process can open is restricted by the parameter icm/max_sockets and ultimately by the operating system. This also restricts the value of icm/max_conn.

Each open ICM connection needs at least one socket. If the ICM is connected with the J2EE Engine as well as with the ABAP Engine, each connection requires two sockets (compare Integration of the SAP J2EE Engine). The SAP Web Dispatcher also requires two sockets for each connection.