Desired maximum lifetime of a persistent connection.
When set, Squid will close a now-idle persistent connection that
exceeded configured lifetime instead of moving the connection into
the idle connection pool (or equivalent). No effect on ongoing/active
transactions. Connection lifetime is the time period from the
connection acceptance or opening time until "now".
This limit is useful in environments with long-lived connections
where Squid configuration or environmental factors change during a
single connection lifetime. If unrestricted, some connections may
last for hours and even days, ignoring those changes that should
have affected their behavior or their existence.
Currently, a new lifetime value supplied via Squid reconfiguration
has no effect on already idle connections unless they become busy.
When set to '0' this limit is not used.