http://php.net/manual/en/opcache.installation.php

Understanding OpCache

Out with the old in with the new

yum install php56u-opcache
yum remove php-pecl-apcu
service php-fpm restart

Run this command in your /var/www/<allyourwebsiteroots>

cd /var/www
find . -type f -print | grep '\.php$' | wc -l
14798

# find your php files and set
# opcache.max_accelerated_files to above that number
# e.g. opcache.max_accelerated_files=16384

My settings

zend_extension=opcache.so
opcache.enable=1
opcache.enable_cli=1
opcache.memory_consumption=128
opcache.interned_strings_buffer=16
opcache.max_accelerated_files=16384
opcache.validate_timestamps=1
opcache.revalidate_freq=60
opcache.fast_shutdown=1
opcache.blacklist_filename=/etc/php.d/opcache*.blacklist