1. A computer system for collecting memory operand access characteristics during transactional execution (TX) of a transaction, the computer system comprising: a memory; and a processor in communications with the memory, wherein the computer system is configured to perform a method, said method comprising: initiating, by a processor, a transactional execution of a set of instructions in a transaction of a program; collecting, by the processor, memory operand access characteristics of the set of instructions during the transactional execution; and storing, by the processor, the memory operand access characteristics upon a termination of the transactional execution of the set of instructions; wherein the initiating is performed by execution of a TBEGIN instruction in the program, by the processor, the TBEGIN instruction specifying a parameter, the parameter designating a storage location for the storing of the memory operand access characteristics.