Newbie Cromwell set memory question

[zoeward-nz]

Hi,

I am a novice BI trying to implement cromwell via GATK exomesinglesample.wdl on a slurm HPC.
I notice the Haplotype Caller stage tries to use all available memory on the system -1024 with:
available_memory_mb=$(free -m | awk '/^Mem/ {print $2}')
let java_memory_size_mb=available_memory_mb-1024

which is causing problems.
Is there a way of setting the maximum memory that this rule can grab in the config file?