I recall for older OS versions, that there was a registry parameter for giving Windows a 'size' for its iconcache database file, but I don't believe it works the same way in Windows 7 or 8. Certainly the parameter name is changed, at the very least, as a search of the Windows 7 registry does not find it under the same name it used to be in XP or other older versions..
I did find a page with a small number of DOS primpt commands to enter, that clear the icondcache and delete the existing iconcache.db file, followed by restarting Windows. This will have Windows rebuild the iconcache on the restart automatically.
That link is:
http://www.sevenforums.com/tutorials/49819-icon-cache-rebuild.html The page above has 2 listed options, with the 1st being to download and run a batch file - I would skip that and do the manual options listed under the 2nd option, first closing any open programs and such, since Windows will be restarted when the last DOD command is entered.
The above does apply to Windows 7 - I don't know if it applies for Windows 8 or not without looking.
I also found a slightly different variation of steps and commands to accomplish the deletion/rebuild of the iconcache.db file:
1. Kill Explorer.exe process. In Windows 7, click Start button > Hold down Ctrl+Shift &
Right Click on empty area in the Start Menu > Click “Exit Explorer”. In Windows 8, you may do so via the Task Manager.
2. Open the command prompt window, type each of the following and after every command, hit the Enter button:
cd /d %userprofile%\AppData\Local
attrib –h IconCache.db
del IconCache.db
start explorer
3. Your Windows Icon Cache will have been rebuilt.
Bob Bone