I will tell you difference between and hope that you will understand easily and will not be confused for that "stack, stock and stuck. The above three words have same pronunciation and most of us in which I am also include used these words in wrong way or don't know difference between them.
So we start with STACK with an A. Stack means a pile of object, typically one that is arrange correctly. If we say "stack of boxes" it means a pile of box arrange correctly.
Next is STOCK with an O. Goods or merchandise stands for Stock kept in a warehouse or in a storage room or place. For example of this is stock of foods, stock of medicines, stock of woods, sugar, ghee and wheat, rice include.
And the last word is STUCK with a U. Something being trapped stands for stuck. Remember the word trapped and keep in mind so you will not confused with stuck and with its meaning. For example stuck in traffic.
above three words have same pronunciation and most of us in which I am also include used these words in wrong way or don't know