[squid-users] cache_mem differs from output in mgr:config

[XUFENG]

My squid's cache_mem in squid.conf differs from output in mgr:config.

[root at squid-cache ~]# /usr/local/squid/bin/squidclient -h 127.0.0.1 -p 80 -w aaaaaa  mgr:config |grep cache_mem
Sending HTTP request ... done.
cache_mem 0 bytes

[root at squid-cache ~]#  /usr/local/squid/sbin/squid -v
Squid Cache: Version 3.4.14
configure options:  '--prefix=/usr/local/squid' '--disable-icap-client' '--disable-wccp' '--disable-wccpv2' '--disable-htcp' '--disable-ident-lookups' '--disable-auto-locale' --enable-ltdl-convenience
[root at squid-cache ~]# cat /usr/local/squid/etc/squid.conf
unique_hostname squid-cache.xufeng.info
visible_hostname squid-cache.xufeng.info
http_port 80 accel
cache_mem 4096 MB
cache_dir ufs /app/cache 8096 32 5120
cache_log /usr/local/squid/var/logs/cache.log
access_log /usr/local/squid/var/logs/access.log
acl PURGE method PURGE
cachemgr_passwd aaaaaa config reconfigure shutdown
http_access allow manager localhost
http_access deny manager
http_access allow PURGE localhost
http_access deny PURGE
cache_mgr xufengnju at 163.com
cache_effective_user squid
cache_effective_group squid
cache_peer 10.1.6.38 parent 80 0 no-query originserver round-robin name=server_xufeng_info
acl sites_xufeng_info dstdomain .xufeng.info
cache_peer_access server_xufeng_info allow sites_xufeng_info

[root at squid-cache ~]# cat /etc/issue
CentOS release 5.11 (Final)
Kernel \r on an \m

[root at squid-cache ~]# uname -a
Linux squid-cache.xufeng.info 2.6.18-407.el5 #1 SMP Wed Nov 11 08:12:41 EST 2015 x86_64 x86_64 x86_64 GNU/Linux

Anything wrong? 
Thank you for your help.