NSPR PL_ClearArenaPool?

Hi experts, I've tried to find some information about 
'PL_ClearArenaPool' of NSPR but could not find anything.

Is this 'public'? 
http://www.mozilla.org/projects/nspr/reference/html/index.html does not 
mention it but it seem NSS is using it.

I was told that NSS 3.13.3 reports the follwoing error on CentOS 6.3

"Cannot load /opt/agent/apache22_agent/lib/libamapc22.so into server: 
/usr/lib64/libnssutil3.so: undefined symbol: PL_ClearArenaPool"

Installed version on that box ...
    - nspr-4.9-1.el6.x86_64
    - nss-3.13.3-6.el6.x86_64

Thanks for any pointers,
Bernhard