1. A computer program product for executing an instruction in a central processing unit, the computer program product comprising: a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for performing a method comprising: obtaining an instruction for execution, the instruction comprising: at least one opcode field to provide an opcode, the opcode identifying a Vector Checksum operation; a first register field to be used to designate a first register, the first register comprising a first operand; a second register field to be used to designate a second register, the second register comprising a second operand; and an extension field to be used in designating one or more registers, wherein the first register field is combined with a first portion of the extension field to designate the first register, and the second register field is combined with a second portion of the extension field to designate the second register; executing the instruction, the executing comprising: adding together a plurality of elements of the second operand to obtain a first result, wherein the adding comprises performing one or more end around carry add operations; based on performing an end around carry add operation and producing a sum, adding a carry out of a chosen position of the sum, if any, to a selected position in a selected element of the first operand; and placing the first result in the selected element of the first operand.