SSRS 2008 R2 missing WorkingSetMaximum line in RSReportSever.config file?

Hi, I have SSRS 2008 R2 configured in SharePoint 2010 integration mode.

I'm looking the RsReportserver.config file to find out about SSRS memory settings (RAM). As per below MSDN link, this config file must have WorkingSetMaximum, WorkingSetMinimum, MemorySafetyMargin and MemoryThresold setting value.     

http://msdn.microsoft.com/en-us/library/ac7ab037-300c-499d-89d4-756f8d8e99f6

However my config is missing WorkingSetMaximum and WorkingSetMinimum lines [see below screenshot where config ONLY shows tag line with MemorySafetyMargin and MemoryThresold setting value] Any idea why the WorkingSetMaximum and Minimum lines are missing from config file?

Thanks.