HeapTool has buttons and displays that help you analyze your system heap usage. The "Current Free Bytes" display indicates the number of free bytes available in your system heap, regardless of fragmentation and unused resources. You may click on the "Compact Heap" button to remove fragmentation and display the largest contiguous space.
The "Purge Heap" button will remove all unused resources, leading to a more accurate display of heap usage. You may find it useful to press the "Purge Heap" button prior to checking the available system heap space either here or in the "About the Finder" utility.
