Likely produced by PHP processes. better check it with GDB to find out what causing it.
yum install gdb
gdb /usr/local/lsws/fcgi-bin/lsphp5 <core_file_name>
maybe submit a bug report to PHP group.
If "LSAPI_ALLOW_CORE_DUMP" is set for lsphp5 external app, you can remove it, it can prevent core files from PHP, however, it is better to find out what is the root cause and fix it.