multiple warnings after xcache installation

[محروم.كوم]

Hello,

My host just installed XCache 1.2.2 on my server as eAccelerator isn't really supported well by vBulletin and vBSEO.

I've modified my config.php to
Code:
$config['Datastore']['class'] = 'vB_Datastore_XCache';
$config['Datastore']['prefix'] = 'forum';
But after uploading the config.php again I'm getting this as a result
Code:
Warning: xcache_isset() [function.xcache-isset]: xcache.var_size is either 0 or too small to enable var data caching in /home/vbstyles/public_html/includes/class_datastore.php on line 557

Warning: xcache_isset() [function.xcache-isset]: xcache.var_size is either 0 or too small to enable var data caching in /home/vbstyles/public_html/includes/class_datastore.php on line 557

lots more of these
Does someone know how to solve this perhaps? __DEFINE_LIKE_SHARE__