help me varnish is not working after implemented the steps mention here

[vijayanand007]

service varnish start
Starting Varnish Cache: [FAILED]
so tried

[root@server1 varnish]# varnishd -p pcre_match_limit=100000 -p pcre_match_limit_recursion=100000 -p thread_pool_stack=192k /etc/varnish/default.vcl Error:
Must be at least 16384
(attempting to set param thread_pool_stack to 192k)

[root@server1 varnish]# service varnish status
varnishd dead but pid file exists