Dissolve yeast in water in a large bowl, and let stand 5 minutes. Stir in 1 3/4 cups flour, cornmeal, oil, and salt to form a soft dough.
Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 5 minutes); add enough of the remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands.
Place dough in a large bowl coated with cooking spray, turning dough to coat top. Cover dough, and let rise in a warm place (85°), free from drafts, 40 minutes or until doubled in bulk.
Punch dough down, and roll into a 15-inch circle on a lightly floured surface. Place dough on a 15-inch pizza pan or baking sheet coated with cooking spray. Top and bake according to recipe directions.
Note: To make 6 individual pizzas, roll dough into 5-inch rounds.