To optimize a garbage collection operation to plural pointer values in a pointer array in a card mark heap by optimizing the garbage collection operation to plural elements corresponding to pointer/data/parameterization.

In a computer system provided with a central processing unit 203 connected to a memory 205, the garbage collection operation to the plural pointer values in the pointer array is optimized. The pointer data parameterization specifies the pattern of pointer allocation relating to a pointer array and parameter making corresponding to a program loop operation. The plural pointer values are stored in the plural elements during the program loop operation without marking the card mark heap during the program loop operation. The garbage collection operation to the plural elements is optimized corresponding to the pointer data parameterization.