Running jobs on PBS pro with more threads


I’m having trouble with running bwa-mem on multiple threads.
Here is my job_conf.xml

                <plugin id="pbs_drmaa" type="runner" load=""/>
                <param id="drmaa_library_path">/opt/drmaa/lib/</param>
                <destination id="cluster" runner="pbs_drmaa">
                	<param id="Resource_List">nodes=1:ppn=4</param>

This runs a job on a node but still with 1 thread, should be 4.
I’m running it on pbs server.
What do I need to change exactly?