1. A method of facilitating processing of transactions within a computing environment, said method comprising: obtaining a transaction begin instruction, the transaction begin instruction comprising an opcode that specifies a transaction begin instruction of a particular type, and a field that specifies a general register save mask to explicitly specify which individually selected one or more registers, if any, of a set of registers are to be saved based on executing the transaction begin instruction, the transaction begin instruction to initiate a transaction, and the general register save mask explicitly specifying the individually selected one or more registers, if any, to be saved at a start of the transaction, the transaction effectively delaying committing transactional stores to main memory until completion of a selected transaction; and executing the transaction begin instruction, the executing the transaction begin instruction comprising saving contents of only the one or more selected registers, if any, explicitly specified in the general register save mask of the transaction begin instruction, and initiating execution of the transaction.