This phase I trial studies the side effects and best dose of stereotactic body radiation therapy when given together with capecitabine before surgery in treating patients with pancreatic cancer that can be removed by surgery. Stereotactic body radiation therapy may be able to send x-rays directly to the tumor and cause less damage to normal tissue. Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving stereotactic body radiation therapy and capecitabine before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed.