This is useful if your server is receiving a lot of http connections. By default the amount of connections is hardcoded into httpd.h file by Cpanel.
To do this, you must recompile Apache using EasyApache and select the "Raise Hard Limits" option. This can be done via WHM --> Apache Update or in shell via /scripts/easyapache
You can also enable this manually in /usr/local/apache/include/httpd.h by uncommenting the HARD_SERVER_LIMIT block in file and restarting apache.