Define a max memory below system memory as default

[RenzoTale88]

Hi,
I got a question concerning the default usage of resources for a nextflow workflow.
Among the parameters I define there are --max_memory, --max_cpus and --max_time, that can in turn be used to limit the resources requested by each task. So far, I've been limiting the max_cpus parameter as follow:
max_cpus = Runtime.runtime.availableProcessors() == 1 ? 1 : Runtime.runtime.availableProcessors() - 1

I'd like to do something similar also for the memory, but I can't find a straight-forward way to do it.
Can you please help me with this?
Thank you in advance!

Andrea