running APC php-caching for all virtual hosts?

[psygarden]

I've always used APC php caching for acceleration of complex php sites (some of my sites are a combination of 3 embedded cms's)

now i've installed apc in my global php.ini (/etc/php5/php.ini) and it's up and running, but i have the impression that it's not loading the amount of items it did on my previous server...

When i look at the cached items i'm missing quite a few of the larger elements that it used to cache on my previous server (without fcgi/ispcp/...)

Question: do i have to enable the module in all my site specific php.ini files?

And if this is the case, i assume i should divide the amount of available memory for the caching among all the sites?

greetings,
Rik