I am running C5 version 5.6.1.2 and when I run a backup it takes a little bit then goes to a page not found. No error message.

When I look in error_log this is what I see

[24-Nov-2013 00:13:08 UTC] PHP Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 32265875 bytes) in /<site_root>/updates/concrete5.6.0.2/concrete/core/libraries/backup.php on line 19

Any ideas. I am obviously running out of some sort of memory, but I am not sure what adjustments to make to accommodate.