Rewriting DataFlash pages
If at all possible, it's nice to keep a number like that in the software (preferably RAM, possibly EEPROM) of the device (e.g., microcontroller) controlling the flash.

If you have to do it in that flash device, you might want to take advantage of the extra 8 bytes per 256-byte flash page in that device to store the pointers; that's one of the suggested uses.


  "System designers can use all of a
  page’s 264 bytes for  storing data.
  Alternatively, the 8 extra bytes per
  page can  be used for error detection
  and correction mechanisms  (EDC) or
  associated control information, such
  as pointers,  flags, and phone message
  routing directions."