It is interesting for capacity planning purpose to know how much socket a webagent running on an apache web server.
Depending on the running mode of the Apache Webagent server (worker/prefork) the caluclation will be different. Apache running in Prefork more is multi-process /single-thread as compare to Apache in worker mode which is multi-process /multi-thread.
In Prefork , you can set maxsocketsperport =1 and minsocketsperport = 1.
As as each process uses only a single thread to communicate with the SiteMinder Policy Server, only one socket is required.
Implementation Guide : Performance Tuning : Web Tier Performance : Web Agent Performance : Increase the Amount of Available Sockets for the Agent
For your socket calculation you should use the following method.
maxprocess x minsocketperport x number of port = max sockets