What I'm about to present I've not tested in VMware Fusion and do not know if it will work.
In VMware Workstation when one selects Edit > Preferences... Memory and in the Additional memory frame one has three choices, "Fit all virtual machine memory into reserved host RAM", "Allow some virtual machine memory to be swapped" and "Allow most virtual machine memory to be swapped". IIRC the default is "Allow some..." and when one changes the default the following option is set/changed in the Host Defaults config(.ini) file as they correspond to the order presented here.
prefvmx.minVmMemPct = "100"
prefvmx.minVmMemPct = "50"
prefvmx.minVmMemPct = "25"
In the Reserve memory frame if the default amount is changed then following option is set/changed in the Host Defaults config(.ini) file.
Syntax: prefvmx.allVMMemoryLimit = "ValueInMegabite"
Example: prefvmx.allVMMemoryLimit = "2048
Additionally while I was changing setting the follow options was set/changed although I didn't get a handle on what triggered it and don't have time at the moment to go back and retest. However you could investigate this on your VMware Workstation install yourself. If I have time later to I will, but no promises.
Syntax: prefvmx.useRecommendedLockedMemSize = "TRUE | FALSE"
Example: prefvmx.useRecommendedLockedMemSize = "FALSE"
In VMware Fusion the Host Defaults config file may not exist, might have to be created manually and the path to which is show in the vmware.log file. Look for "HOST DEFAULTS" and in will probably be pointing to "/Library/Preferences/VMware Fusion/config".
Maybe one of the VMware developers will see this thread and comment whether or not these options will work with VMware Fusion or not however I doubt it would hurt to try. Also make sure all Virtual Machines are shutdown, not suspended and VMware Fusion closed when editing the config file.