1. In a computer system having address translation tables for dynamically translating virtual addresses to main storage addresses, a method for invalidating a range of two or more address translation table entries, the method comprising the steps of: determining from an opcode of a machine executable instruction to be executed, that the instruction is configured to initiate execution of an invalidate and clear operation; and executing the instruction, the executing step comprising the step of: invalidating the range of two or more address translation table entries.