If you have not already done so, in the Change Center of the Administration Console, click Lock & Edit (see Use the Change Center).
Expand
Compatibility Security > Caching
Realms and click the name of the Caching realm.
Expand
Configuration > ACL and
check Enable ACL Cache.
Set the size and duration attributed for the ACL cache.
Click Save to save your
changes.
To activate these changes, in the Change Center of the Administration Console, click Activate Changes. Not all changes take effect immediately—some require a restart (see Use the Change Center).