What the average stack is? If twice or more than you have, you may call ministack all-in. His range is very large. You often are over him.
Yes, range is very large. But if you take the range of all-in hands is 22+, 99+, A2x+, K2x+, Q2x+, J9x+, T9x+, 56s, 67s, 68s, 78x, 89x, T8x, J8x then you got 64 hands of 1326 its 85:15%, 192 of 1326 - 70:30%. This is 156 dominated thee hands (11% of all hands). 240 of 1326 - 55:45% (coin flip) (18% of all hands). And only 36 of 1326 - 15:85% dominant over you (0,03% of all hands)
So, with 20bb you must call all coin flip hands as this is the solution with the plus sign imho. That is 396 vs 36 hands or 91% of 100% to call.
My answer is call