Patent US 5,613,086

A LOCK PAGE instruction is provided for locking a page of real storage using a virtual address. The LOCK PAGE instruction includes an operation code which specifies the operation to be performed, a first operand which contains the value of the real address obtained during execution of the LOCK PAGE instruction and a second operand which contains the value of the virtual address of the page to be locked during execution of LOCK PAGE. LOCK PAGE enables an address page or a data page to be locked without requiring the entire address space to be locked. A page is locked when a lock control bit in general register 0 is zero, the page is valid in main storage and a lock bit located in a page table entry is zero. In addition to the above, the technique used by an operating system service for reclaiming a page of real storage is altered to intersect with the LOCK PAGE facility.