The LRA instruction works differently depending on addressing mode you use. In 64-bit mode, the LRA instruction results in a 64-bit real address stored in a 64-bit GPR. In 24-bit and 31-bit modes, the LRA instruction results in a 31-bit real address stored in a 32-bit GPR. The LRA instruction cannot be used to obtain the real address of locations backed by real frames above 2 gigabytes in 24-bit or 31-bit addressing mode. For those situations, use the LRAG instruction instead of LRA. All programs that issue an LRA instruction must be prepared to handle a 31-bit result if the virtual storage address specified could have been backed with central storage above 16 megabytes, or a 64-bit result if the virtual storage address specified could have been backed with central storage above 2 gigabytes. Issue LRA only against areas that are fixed. The TPROT instruction can be used to replace the LRA instruction when a program is using it to verify that the virtual address is translatable and the page backing it is in real storage.