cat httpd.conf | grep MaxClients
# MaxClients: maximum number of server processes allowed to start
MaxClients         512
# MaxClients: maximum number of simultaneous client connections
MaxClients         512
# MaxClients:   max number of threads we can have (1 thread == 1 client)
MaxClients                 50

apachectl -v
Server version: Apache/2.0.52

WARNING: MaxClients of 512 exceeds ServerLimit value of 256 servers,
 lowering MaxClients to 256.  To increase, please see the ServerLimit
 directive.