abap/heap_area_total: Total Quota for Heap Memory 

This parameter sets the maximum heap memory limit that all work processes of an SAP application server can allocate. You can use this upper limit to restrict the swap space usage of an SAP application server to a specific amount. You can find more details on this topic under Functionality of the SAP Memory Management System.

This value ensures that even at maximum swap space usage of the SAP system and during normal operation, at least 100 MB swap space (or approximately 10-15%) remains free. See also Swap Space Requirements