Catalyzes two subsequent steps in gluconeogenesis: the aldol condensation of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GA3P) to fructose-1,6-bisphosphate (FBP), and the dephosphorylation of FBP to fructose-6-phosphate (F6P). beta-D-fructose 1,6-bisphosphate + H2O = beta-D-fructose 6-phosphate + phosphate beta-D-fructose 1,6-bisphosphate = D-glyceraldehyde 3-phosphate + dihydroxyacetone phosphate Optimum pH is 8.0 for FBP phosphatase activity and 7-8.5 for the FBP aldolase activity. Highly thermostable. Survives boiling for 1 hour. Carbohydrate biosynthesis; gluconeogenesis. Homooctamer; dimer of tetramers. Consists of a single catalytic domain, but remodels its active-site architecture via a large structural change to exhibit dual activities. Belongs to the FBP aldolase/phosphatase family.