private void checkExtend(final int size) {
        final T[] originalStack = this.stack;
        if (size >= originalStack.length) {
            final int copyStackSize = originalStack.length << 1;
            final T[] copyStack = newStack(factory.getType(), copyStackSize);
            System.arraycopy(originalStack, 0, copyStack, 0, originalStack.length);
            this.stack = copyStack;
        }
    }
@author netspider
@author Woonduk Kang(emeroad)
@author jaehong.kim
agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/context/DefaultCallStack.java