Quick Question about MemUsage() and flushmem()

I've just started learning bmax and was trying to understand try/catch blocks and exceptions etc when i noticed 4k difference between having the first flushmem() comented or not. Any idea what flushmem() is flushing before my program has done anything?

Type TExcepTest Extends TBlitzException
	Method ToString$()
		Return "my test"
	End Method
EndType

rem
FlushMem()
end rem

Print MemUsage()

Try
	Throw New TExcepTest
Catch ex:Object
	Print MemUsage()
	Print ex.tostring$()
	Print MemUsage()
EndTry


FlushMem()
Print MemUsage()

End

uncomented the output window shows

H:/bmax/Projects/excep1/excep1.debug.exe
12352
14912
my test
14912
14912

commented it shows

H:/bmax/Projects/excep1/excep1.debug.exe
16472
19032
my test
19032
14912

I know its only a few kb and may be of no consiquence but it would be nice to know whats being flushed at the start.

Dereferenced objects used during BlitzMAX's upstart.

Cheers FlameDuck.