one simple question

[chungwei Hsiung]

Hello..
  I have a simple question, but I am not sure what the answer is. If anyone can possibly help me, it is really appreciated.
  I compile a test C file. I notice there are a few lines at the beginning of the assembly code. I want to know what it means, but can't figure out one of them. Can anyone tell me what the following line does please?

and    $0xfffffff0,%esp

best regards
Chungwei