A method of controlling execution of a transaction in a computing environment, the method comprising steps of: initiating, by a processor, execution of a transaction in a transaction mode via a transaction begin instruction, the transaction begin instruction to begin any one of a first type of transaction or a second type of transaction, the transaction comprising a plurality of instructions to be executed, and the transaction begin instruction explicitly indicating by a field of the transaction begin instruction the first type of transaction or the second type of transaction being initiated; based on the transaction being the second type of transaction, the execution setting a condition code to a first value, based on being in transaction mode, effectively delaying committing transactional stores to main memory until completion of a selected transaction; based on the transaction aborting, determining the type of transaction initiated, the type of the transaction being the first type of transaction or the second type of transaction, and the determining being based on the field of the transaction begin instruction; based on the transaction aborting and the transaction being the first type of transaction, resuming execution at the transaction begin instruction; and based on the transaction aborting and the transaction being the second type of transaction, setting the condition code to a second value, wherein the second value indicates a next sequential instruction, following the transaction begin instruction, that is receiving control from the abort, and resuming execution at the next sequential instruction directly following the transaction begin instruction in program order; wherein the first type of transaction is a constrained transaction having a plurality of restrictions associated therewith and defined to successfully complete if the plurality of restrictions are followed, and the transaction begin instruction is a transaction begin constrained instruction, and wherein the plurality of restrictions associated with the constrained transaction include: only a subset of instructions is available for inclusion in the constrained transaction; the constrained transaction is limited to a predetermined number of instructions to be executed in the constrained transaction, the predetermined number of instructions being no more than 32 instructions, not including transaction begin and transaction end instructions; the instructions in the constrained transaction are to be within 256 contiguous bytes of storage; storage operands of the constrained transaction access no more than 4 octowords; and the constrained transaction is limited to a single nesting level, and wherein the second type of transaction is a nonconstrained transaction, the nonconstrained transaction not limited by the plurality of restrictions associated with the constrained transaction. initiating, by a processor, execution of a transaction in a transaction mode via a transaction begin instruction, the transaction begin instruction to begin any one of a first type of transaction or a second type of transaction, the transaction comprising a plurality of instructions to be executed, and the transaction begin instruction explicitly indicating by a field of the transaction begin instruction the first type of transaction or the second type of transaction being initiated; based on the transaction being the second type of transaction, the execution setting a condition code to a first value, based on being in transaction mode, effectively delaying committing transactional stores to main memory until completion of a selected transaction; based on the transaction aborting, determining the type of transaction initiated, the type of the transaction being the first type of transaction or the second type of transaction, and the determining being based on the field of the transaction begin instruction; based on the transaction aborting and the transaction being the first type of transaction, resuming execution at the transaction begin instruction; and based on the transaction aborting and the transaction being the second type of transaction, setting the condition code to a second value, wherein the second value indicates a next sequential instruction, following the transaction begin instruction, that is receiving control from the abort, and resuming execution at the next sequential instruction directly following the transaction begin instruction in program order; wherein the first type of transaction is a constrained transaction having a plurality of restrictions associated therewith and defined to successfully complete if the plurality of restrictions are followed, and the transaction begin instruction is a transaction begin constrained instruction, and wherein the plurality of restrictions associated with the constrained transaction include: only a subset of instructions is available for inclusion in the constrained transaction; the constrained transaction is limited to a predetermined number of instructions to be executed in the constrained transaction, the predetermined number of instructions being no more than 32 instructions, not including transaction begin and transaction end instructions; the instructions in the constrained transaction are to be within 256 contiguous bytes of storage; storage operands of the constrained transaction access no more than 4 octowords; and the constrained transaction is limited to a single nesting level, and wherein the second type of transaction is a nonconstrained transaction, the nonconstrained transaction not limited by the plurality of restrictions associated with the constrained transaction.