While it has been extensively studied on how to model and measure a scholar's research impact (e.g., citation analysis), there have been very few studies that systematically collect and quantify a scholar's service impact to scientific communities. To address this lack of studies, we have developed a prototype digital library, named as Gatekeeper, that crawls, extracts, and quantifies scholars' service impacts based on their roles as gatekeepers in Computer Science conferences. Continuing this effort, in this work, we further theoretically analyze and improve the understanding on the expected behavior of three quantification measures (i.e., Gindexes) being used in Gatekeeper. In addition, we demonstrate that the stretched-exponential model fits significantly better than three other heavy-tail models (i.e., power-law, log-normal, and parabolic-fractal) in capturing scholars' service impacts via three quantification measures. Finally, using the analyzed quantification measures, we present leading scholars and conferences with respect to their service impacts. Our prototype is available at: https://gatekeeper.ist.psu.edu.