[squid-users] Squid crashes, but generates no core file

I need a hint, squid crashes, but generates no core file.
It's started this way (from daemontools' supervise):

------------ snip --------------
mv /squid-cache0/core /squid-cache0/core-/bin/date +%T

cd /squid-cache0
touch /squid-cache0/core
chmod 666 /squid-cache0/core

tail --lines=50 /var/log/squid/cache.log | /usr/bin/mail -s "hostname: Squid restarted" xxxxx@charite.de
/bin/sync

ulimit -n 4096
exec /usr/sbin/squid -NsYC
------------ snip --------------

How do I get a corefile?

-- 
Ralf Hildebrandt (i.A. des IT-Zentrum)          Ralf.Hildebrandt@charite.de
Charite - Universitätsmedizin Berlin            Tel.  +49 (0)30-450 570-155
Gemeinsame Einrichtung von FU- und HU-Berlin    Fax.  +49 (0)30-450 570-962
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