client server protocol

Sorry, I'm new to both C and Unix.

Previously at my course, we had been lecture to create a simple client and server connection using TCP protocol, stream socket and fork system call. But I found that the listen system call at server process had limit the maximum connection to 5, but I couldn't found any related information which show me how to enlarge the maximum connection.

If I want to change the application to be able to cope with thousand of connection at one time, what should I change? or is that I had to change for other protocol?

Where can I found any documentation which had information related to this?

Appreciate for any respond