1. A computer program product for performing a load page table entry address (LPTEA) function in a computer system of a machine architecture, said computer system configured to translate a virtual address into a translated address of a block of data in main storage, the computer system having a hierarchy of translation tables for translation of said virtual address, said load page table entry function defined for said machine architecture, the computer program product comprising: a non-transitory storage medium readable by said computer system, said computer readable medium storing instructions for performing: executing, by a processor, a machine instruction, said machine instruction comprising an opcode for a Load Page Table Entry Address (LPTEA) instruction, the executing comprising: based on determining a format control field in a segment table entry has an enabled value, saving, by the processor, a segment table entry address in a first general register; and based on determining the format control field has a not enabled value, saving, by the processor, a page table entry address in said first general register.