Eliot Miranda uploaded a new version of System to project The Trunk:
http://source.squeak.org/trunk/System-eem.943.mcz

==================== Summary ====================

Name: System-eem.943
Author: eem
Time: 30 March 2017, 1:13:51.515243 pm
UUID: 9668f030-a0c9-42bf-a030-8ffd7af62ed5
Ancestors: System-eem.942

Eliminate an explicit reference to MethodContext in lowSpaceThreshold and make it more accurate for 64-bits.

=============== Diff against System-eem.942 ===============

Item was changed:
  ----- Method: SmalltalkImage>>lowSpaceThreshold (in category 'memory space') -----
  lowSpaceThreshold 
  	"Answer the low space threshold. When the amount of free memory (after garbage collection)
  	 falls below this limit, the system is in serious danger of completely exhausting memory and
  	 crashing. This limit should be made high enough to allow the user open a debugger to diagnose
  	 a problem or to save the image.  In a stack-based VM such as Cog contexts for activations in
  	 the stack zone will have to be created as the debugger opens, requiring additional headroom."
  
  	| slotsForDebugger slotsForContextsOnStackPages |
  	slotsForDebugger := 65536. "Arbitrary guess"
  	slotsForContextsOnStackPages :=
  		(self vmParameterAt: 42)
  			ifNil: [0]
  			ifNotNil:
  				[:numStackPages| | headerSize numActivationsPerPage maxContextSize |
+ 				numActivationsPerPage := 40. "Design goal of the Cog & Stack VMs"
+ 				headerSize := 8 / self wordSize. "64-bits for Spur"
+ 				maxContextSize := thisContext class instSize + CompiledMethod fullFrameSize + headerSize.
- 				numActivationsPerPage := 40. "Design goal of the Cog VM"
- 				headerSize := 2. "64-bytes for Spur"
- 				maxContextSize := MethodContext instSize + CompiledMethod fullFrameSize + headerSize.
  				numStackPages * numActivationsPerPage * maxContextSize].
  	^slotsForDebugger + slotsForContextsOnStackPages * self wordSize!