Error created viewing any page

any idea what this might be caused by?

Warning: require_once(): Unable to allocate memory for pool. in /var/www/html/mysite/piwik/core/FrontController.php on line 117

Backtrace -->

#0 Piwik_ErrorHandler(…) called at [/var/www/html/mysite/piwik/core/FrontController.php:117]
#1 Piwik_FrontController::dispatch(…) called at [/var/www/html/mysite/piwik/core/FrontController.php:117]
#2 Piwik_FrontController->dispatch(…) called at [/var/www/html/mysite/piwik/index.php:53]

i looked at the server’s memory usage and space remains available - so the obvious is not the cause here.

The memory limit defined in the php.ini file is probably too low.