A method for executing a program region by a computer system with transactional memory support is disclosed. The computer system uses hierarchical locks for executing the program region. Determination is conducted whether a first condition related to a transaction abort is satisfied in beginning a transaction for the program region. If the first condition is satisfied, a bottom level lock corresponding to a bottom level resource among available resources is acquired to execute the program region in the transaction. If a second condition is determined to be satisfied, a next level lock corresponding to next level resource is acquired. If the acquired lock is a top level lock corresponding to a top level resource, the program region is executed without using the transaction.