how to control xticklabel location?

Hi

I change y limit, then my xticklabel location is aligned with previous y limits.

For example, in the attached figure, original minimum y is -16. when I change y limit to -266. the xticklabel move up to the location where -16 was.

I have been playing with this all morning and i don't know how to do it.

so could you please help me on how do i control the location of xticklable after changing y limits? I want the xticklabel always under the x-axis.

Thank you so much.

Here are my codes

    % remove current tick first 
    set(hrightsubplot,'XTick',[])
    set(hrightsubplot,'Xticklabel',{[]})

    set(hrightsubplot,'xtick',[startdatenum:dayinterval:enddatenum]);
    datetick(hrightsubplot,'x','mmm-dd-YYYY','keepticks','keeplimits');  

    rotateticklabel(hrightsubplot,45);

I think it is due to datetick(). what does the keepticks do? I really don't like datetick().