Hey,
I installed APCu using pecl
"pecl install apcu"
APCu was installed successfully, but I can't enable it.
I created apcu.ini in : /opt/plesk/php/5.6/etc/php.d
apcu.ini contains this rows:
extension = apcu.so
apc.enabled=1
apc.shm_segments=1
apc.shm_size=128M
apc.ttl=3600
apc.user_ttl=7200...