How does PBS interact with compute node ulimits?

I want to understand in general how the Linux limits are controlled on the compute nodes.

Specifically, we are trying to prevent core files unless the user explicitly enables them. We want:

unlimit -S -c 0 and ulimit -H -c unlimited

set by default. We set those two ulimits in /opt/pbs/lib/init.d/limits.pbs_mom but it had no effect. We also set /etc/pbs.conf PBS_CORE_LIMIT to 0 and restarted PBS and that didn’t prevent cores. AFAICT ulimits are always unlimited. We are also unaware of any integration with PAM so /etc/security/limits.conf doesn’t appear to be an option.

Anybody have a way they successfully control ulimits?

Our environment is SLES15 SP3, PBSPro 2022.1.1