With the advent of deep sub micron era, design closure is becoming harder to achieve. In high-level synthesis, slack is a very effective means of tolerating uncertainties. Thus, several research efforts have been paid to study the slack-driven high-level synthesis problem. However, previous works cannot actually maximize the total slack value, because they are limited to either the operation scheduling stage or the resource binding stage. In this paper, we study the simultaneous operation scheduling and resource binding for the maximization of the total slack value. An integer linear programming approach is proposed for formally draw up the slack-driven high-level synthesis problem. Note that our approach guarantees maximizing the total slack value. Compared with the combination of previous works (i.e., slack-driven operation scheduling followed by slack-driven resource binding), experimental data show that our approach can greatly reduce the total slack value without any design overhead.