Note: You are currently viewing documentation for Moodle 3.3. Up-to-date documentation for the latest stable version of Moodle is probably available here: admin/environment/php setting/memory limit.

admin/environment/php setting/memory limit

From MoodleDocs

memory_limit should be at least 96M. Large sites may need much more. PHP 5.2.x requires higher memory_limit values than previous versions of PHP. 64bit operating systems require even more memory.