There was a time when you had to restart a lot of stuff after editing registry entries like : KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\HeapSettings SPRequestStackTrace = 1
to get the root cause of memory leaks and all that stuff.
Now you have property SPWebService.CollectSPRequestAllocationCallStacks . This is a diagnostic setting that facilitates the debugging of leaks of SPSite and SPWeb objects. If not disposed properly these objects can hold onto large amounts of memory. By enabling this setting, traces in the trace log that report leaks will contain callstacks. However, callstack collection is expensive so this should only be enabled during a brief diagnostic period.
$MySvc = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$MySvc.CollectSPRequestAllocationCallStacks = $true | $false