Manual:$wgMsgCacheExpiry

From MediaWiki.org

Localization: $wgMsgCacheExpiry
When a message in cache expires (in seconds).
Introduced in version:	1.2.0
Removed in version:	still in use
Allowed Values:
Default Value:	86400

Other settings: Alphabetical | By Function

[edit] Details

Expiry time for the message cache key (in seconds).