Patent ID: 8376360

Claim:
A sheet stacking apparatus which stacks sheets that are discharged from an image forming apparatus, comprising: first and second stacking trays configured to stack sheets; a detection unit configured to detect a sheet stacking amount on the first stacking tray; a setting unit configured to manually set a first upper limit on stacking amount for limiting the number of sheets stacked on the first stacking tray, wherein the first upper limit on stacking amount is equal to or less than a maximum sheet stacking amount on the first stacking tray; and a control unit configured to stop stacking of sheets on the first stacking tray and stack sheets on the second stacking tray in a case where the sheet stacking amount reaches the first upper limit on stacking amount, wherein the setting unit includes a selection unit configured to select a method of setting the first upper limit on stacking amount, and wherein the selection unit selects a first method of setting, as method of setting the first upper limit, an elapsed time from start of stacking sheets on the first stacking tray and a second method of setting parameters except the elapsed time.