For a project I try to build a dual supply for opamps in a device. I bought the MC34063 to invert the DC. The device should be portable, however, the standard schematic in the datasheet uses some very big capacitors.

The Question:
Can I use smaller capacitors? 

I don't know what the function of the capacitors is. Should they store charge or act as some sort of cutoff resistor? The datasheet has some formula to make calculations, but those include the frequency parameter, even though its DC power. I will require less than 8V and 20 mA from the IC.

Best and thanks!