1. A method for executing instructions of a transaction in a transaction execution (TX) computing environment with transactional memory, the method comprising: executing, by a processor, a latent modification instruction (LMI) within the transaction, the transaction comprising a set of target instructions following the LMI in program order in an instruction stream, each of the target instructions having an associated function, the LMI at least partially specifying a substitute function to be substituted for each of the associated functions, the LMI being an executable instruction distinct from the set of target instructions; and executing, by the processor, a next sequential instruction (NSI) and at least one of the target instructions within the transaction, the NSI following the LMI in program order in the instruction stream, wherein the executing the at least one of the target instructions employs the substitute function at least partially specified by the LMI, wherein a postfix instruction follows the set of target instructions and precedes a transaction end instruction in program order in the instruction stream, the postfix instruction being an instruction that designates that no instructions following it in the instruction stream are modified by the LMI.