Before setting swapsize stop all services from netimsh shell. In this order. On Core Node from netimsh #stop all. Then after core has stopped. On Manager Node, #stop all.
In netimsh use the command:
# system swapsize <mention size in number>
Here for example I'm incresing the swap memory by 8 GB
# system swapsize 8
you can validate the swap memory using below command in bash,
# free -h
Start all services on Manager Node from netimsh. #start all. (Depending on Netim version you may need to all start all on Core Node).