Solved Squid Proxy 【reference_age】settting

Hi guys
In the Linux, I can setup reference_age = 1 days will cause objects to be removed, if they have not been accessed for 1 days.

In the freebsd , It will say
2016/10/17 15:34:07| /usr/local/etc/squid/squid.conf:24 unrecognized: 'reference_age'

How to fix this problem , thanks
Thanks your reply , I using another way to achieve this !!
killall squid
rm -rf /var/spool/squid/
mkdir /var/spool/squid && chown squid:squid /var/spool/squid >>/var/log/"$(date "+%Y-%m-%d")"-proxy-err.log 2>&1
squid -z && /usr/local/etc/rc.d/squid start >>/var/log/"$(date "+%Y-%m-%d")"-proxy-err.log 2>&1
And I put this shell script in /etc/crontab
Best not to modify /etc/crontab, it's likely to get overwritten with updates. Use root's crontab(1) for things like this.