/usr/bin/php: error while loading shared libraries: libXau.so.6: failed to map segment from shared object: Cannot allocate memory
Caused by: Did you try to update memory settings in php config? Seems if you do this, you also need to increase the amount available to Apache, i.e.
vi /usr/local/apache/conf/httpd.conf
And set the RLimitMEM to something like 651048618
See this reference.