PHP APC is cache module provided by pecl and can be install via pecl. I assume you already had installed pecl.
sudo pecl install apc
That will install APC. After this let’s create apc.ini in /etc/php.d/.
sudo vim /etc/php.d/apc.ini
And paste this in it: [vim: to start writing hit Insert key, when finished writing hit Esc key. Ctrl+z twice to save and exit OR :wq]
Open /usr/share/pear/pearcmd.php for writing:
sudo vim /usr/share/pear/pearcmd.php
Paste/type this in it for memory management at the beginning:
Normally i keep it at 32MB, but choice is yours.
Now restart the web server and check it via phpinfo().
To upgrade it in future:
sudo pecl upgrade apc