How do I save PNG images using the MATLAB PCT without running into a RAM ceiling?

Matlab Gurus,

I'm noticing that I run into a RAM ceiling when using parfor to save PNG files, but this is not the case when using parfor to save FIG files (I tried up to 100,000 FIG files, and RAM held mostly steady.)

The code below allows you to see what I'm talking about ...

• To plot PNG images using a parfor loop, run the code with method = 'png' and either persist = 0 or persist = 1.
• To plot FIG files, run the code with method = 'fig'. (No persist option applies in this case.)

Before executing the code, make sure to have first ...

• set up a parallel pool,
• created the PNG_SavePath and FIG_SavePath directories shown in the code, and
• opened up the Windows Resource Monitor.

And in case you're wondering, my setup had the following specs ...

• Windows 7, 16 cores, 16GB RAM
• MATLAB 2015a using parpool(14)

 function par_peaks
     method = 'png';
     numfigs = 1000;
     persist = 0; % When = 1, I'm attempting to ensure that a new GUI
                  % window is not created if one already exists. Wasn't
                  % sure if this was contributing to the RAM blasting
                  % off or not. I'm still not sure if this works like
                  % I think it does in a multi-worker situation. One
                  % thing is for sure ... the 'persist' option makes
                  % no difference: RAM still blows up when plotting
                  % PNG files. Maybe I implemented the 'persist'
                  % code badly?
     if strcmpi(method,'png')
         PNG_SavePath = 'C:\ParPlotter\PNG_SavePath\';
         if persist == 0
             parfor ii = 1 : numfigs
                 PNG_Handle = figure('visible','off');
                 t = getCurrentTask();
                 PNG_Name = horzcat('PNG ',num2str(ii),' - TaskID ',num2str(t.ID),'.png');
                 [X,Y,Z] = peaks(25);
                 surf(X,Y,Z);
                 az = randi([0,359],1,1);
                 el = randi([-90,90],1,1);
                 view(az,el);
                 title(PNG_Name);
                 saveas(gcf,[PNG_SavePath,PNG_Name]);
                 close(PNG_Handle);
             end
         elseif persist == 1
             parfor ii = 1 : numfigs
                 t = getCurrentTask();
                 GUI_Name = horzcat('TaskID ',num2str(t.ID));
                 GUI_Handle = findobj('type','figure','name',GUI_Name);
                 if isempty(GUI_Handle)
                     figure('name',GUI_Name,'visible','off');
                 else
                     clf(GUI_Handle);
                 end
                 PNG_Name = horzcat('PNG ',num2str(ii),' - TaskID ',num2str(t.ID),'.png');
                 [X,Y,Z] = peaks(25);
                 surf(X,Y,Z);
                 az = randi([0,359],1,1);
                 el = randi([-90,90],1,1);
                 view(az,el);
                 title(PNG_Name);
                 saveas(gcf,[PNG_SavePath,PNG_Name]);
                 % close(PNG_Handle);
             end
         end
     elseif strcmpi(method,'fig')
         FIG_SavePath = 'C:\ParPlotter\FIG_SavePath\';
         parfor ii = 1 : numfigs
             FIG_Handle = figure('visible','off');
             t = getCurrentTask();
             FIG_Name = horzcat('FIG ',num2str(ii),' - TaskID ',num2str(t.ID),'.fig');
             [X,Y,Z] = peaks(25);
             surf(X,Y,Z);
             az = randi([0,359],1,1);
             el = randi([-90,90],1,1);
             view(az,el);
             title(FIG_Name);
             savefig(FIG_Handle,[FIG_SavePath,FIG_Name],'compact');
             close(FIG_Handle);
         end
     end
  end

What is the proper way to do this? SPMD block? MDCS?