i've always found that those rear mount kickstands aren't all that stable. every bike i've had or seen them on tended to want to roll around in a circle.
best bet is to find a Wald kickstand. i know you can still buy them, but i haven't checked on the quality of the newer ones. if they're the same as the old ones, then they're nice heavy duty steel ones.
i've seen newer kickstands on bikes that are pencil thin, and if you have one of those, you might as well just throw your bike on the ground everytime you go to 7-11.