The amount of memory in bytes that a process needs to execute efficiently, for an operating system that uses page-based memory ...

The amount of memory in bytes that a process needs to execute efficiently, for an operating system that uses page-based memory management. If an insufficient amount of memory is available (< working set size), thrashing will occur. If this information is not known, NULL or 0 should be entered.  If this data is provided, it could be monitored to understand a process' changing memory requirements as execution proceeds.