1. A system for allocating shared memory of differing properties to shared data objects, comprising: a hybrid stack creator configured to create, in said shared memory, a hybrid stack data structure having a lower portion having a more favorable property and a higher portion having a less favorable property; and a data object allocator associated with said hybrid stack creator and configured to allocate storage for shared data object in said lower portion if said lower portion has a sufficient remaining capacity to contain said shared data object and alternatively allocate storage for said shared data object in said higher portion if said lower portion has an insufficient remaining capacity to contain said shared data object.