Instruction processing is performed for an instruction. The instruction is configured to perform a plurality of functions, in which a function of the plurality of functions is to be performed in a plurality of processing phases. A processing phase is defined to store up to a select amount of data. The select amount of data is based on the function to be performed. At least one function of the plurality of functions has a different value for the select amount of data than at least one other function. A determination is made as to whether a store into a designated area occurred based on processing a select processing phase of a select function. Based on determining that the store into the designated area occurred, an interrupt is presented, and based on determining that the store into the designated area did not occur, instruction processing is continued.