Manual:$wgParserCacheExpireTime

Parser Cache: $wgParserCacheExpireTime
Expiration time (in seconds) of cached parser information
Introduced in version:1.6.0 (r12542)
Removed in version:still in use
Allowed values:Unspecified
Default value:60 * 60 * 24 (1.39+)
86400 (1.6-1.38)

Details edit

Expiration time (in seconds) of cached parser information. Defaults to 24 hours.