1. In a multi-processor system having multiple memory hierarchies each having an associated processor, a method for establishing victim caching among the memory hierarchies, said method comprising: responsive to requiring a castout from a first of the memory hierarchies, sending a cast in request from the first memory hierarchy to a second of the memory hierarchies, wherein said cast in request includes a cast out tag identifier of the first memory hierarchy; and responsive to the cast in request, retrieving cast out data from the first memory hierarchy to the second memory hierarchy utilizing the cast out tag identifier.