Why is it not possible to push a byte onto a stack on Pentium IA-32?

Question

I\'ve come to learn that you cannot push a byte directly onto the Intel Pentium\'s stack, can anyone explain this to me please?

The reason that I\'ve been given is b

Answer 1

The stack pointer must be (for some optimalization reasons) 4B aligned -> it should be divisible by four (and, therefore, have last 2 bits zero).