Apcu is a php module used for data caching. Steps for the installation is as follows
1. Login in to server via SSH with root access
2. Install necessary pcre-devel package prior to the APCu installation
yum install pcre-devel
3. Then install APCu via PECL repository
pecl install channel://pecl.php.net/APCu-4.0.10
4. restart apache
/etc/init.d/httpsd restart