Check the settings and add/adjust as follows:

Find the configuration file:

root@serv [~]# /usr/local/apache/bin/httpd -V
Server version: Apache/2.2.27 (Unix)
Server built:   Jun 12 2014 01:44:45
Cpanel::Easy::Apache v3.24.19 rev9999
Server's Module Magic Number: 20051115:33
Server loaded:  APR 1.5.0, APR-Util 1.5.3
Compiled using: APR 1.5.0, APR-Util 1.5.3
Architecture:   64-bit
Server MPM:     Prefork
  threaded:     no
    forked:     yes (variable process count)
Server compiled with....
 -D APACHE_MPM_DIR="server/mpm/prefork"
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses disabled)
 -D APR_USE_SYSVSEM_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=128
 -D HTTPD_ROOT="/usr/local/apache"
 -D SUEXEC_BIN="/usr/local/apache/bin/suexec"
 -D DEFAULT_PIDLOG="logs/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_LOCKFILE="logs/accept.lock"
 -D DEFAULT_ERRORLOG="logs/error_log"
 -D AP_TYPES_CONFIG_FILE="conf/mime.types"
 -D SERVER_CONFIG_FILE="conf/httpd.conf"

The config file is usually at:
/usr/local/apache/conf/httpd.conf

Add/Edit the config:

Start Servers 32
Minimum Spare Servers 32
Maximum Spare Servers 256
Server Limit 2000
Max Clients 1500
Keep-Alive On