How to get cursor information of data tips using call back of a push buttion?

I have a fairly simple code. All I want is user to select multiple data tips (Alt+left mouse button) from a plot and on clicking a push button, the position and data index of the data tips be written in a structure. The command, c_info = cursorMode.getCursorInfol; gives me the required output but not when used in a callback function. Please suggest a way to assign the above command to a push button. Thanks for the help! First draft of the code is herewith:

   function [] = GUI_me(varargin)
fh = figure('units','pixels',...
              'position',[200 100 500 560],...
              'menubar','none',...
              'name','GUI_1',...
              'numbertitle','off',...
              'resize','off');
              z = peaks;
              plot(z(:,30:35))
              dcm_obj = datacursormode(fh);
set(dcm_obj,'DisplayStyle','datatip',...
'SnapToDataVertex','off','Enable','on')       
pb = uicontrol('style','push',...
                 'units','pix',...
                 'position',[10 10 180 40],...
                 'fontsize',14,...
                 'string','Done',...
                 'callback',{@pb_call});
pb2 = uicontrol('style','push',...
                 'units','pix',...
                 'position',[300 10 180 40],...
                 'fontsize',14,...
                 'string','Clear data tips',...
                 'callback',{@pb2_call});
function [] = pb2_call(varargin) % Clears user selected data tips 
cursorMode = datacursormode(gcf);
cursorMode.removeAllDataCursors();
function [] = pb_call(varargin) % Returns the position and data index of selected data tips 
% Callback for pushbutton.
cursorMode = datacursormode(gcf);
c_info = cursorMode.getCursorInfo;