How to prevent databse from being overwritten in xmem after a power cycle?

After allocating +13kB in xmem using _xalloc(&tempsz, 0, XALLOC_BB) and itializing it, how do I prevent reallocating memory with default data(which are out-of-date) after a power cycle?  is there something I'm missing?


// begin quasi pseudo-code...

#define BLOCK_START_MEMBER             ((long)0x3A8446F7)
#define BLOCK_END_MEMBER                 ((long)0x7F6448A3)

#define BLOCK_START_NODE                 ((long)0x3A8446F8)
#define BLOCK_END_NODE                 ((long)0x7F6448A4)

#define BLOCK_START_DIGITAL             ((long)0x3A8446F9)
#define BLOCK_END_DIGITAL             ((long)0x7F6448A5)

#define BLOCK_START_ANALOG             ((long)0x3A8446FA)
#define BLOCK_END_ANALOG                 ((long)0x7F6448A6)


void main(void)
{

  
   long tempsz;
   far char *pMemBlock_Member, *pMemBlock_Node, *pMemBlock_Digital,*pMemBlock_Analog;
   far long *pStartAddrMark_Member, *pStartAddrMark_Node, *pStartAddrMark_Digital, *pStartAddrMark_Analog;
   far long *pStopAddrMark_Member, *pStopAddrMark_Node, *pStopAddrMark_Digital, *pStopAddrMark_Analog;
   

   //--------------------------Allocate Memory Block for Members----------------
   //_xalloc the data block and calculate marker locations
   tempsz = (MAX_MEMBERS * sizeof(Member_t));
   tempsz += 2 * sizeof(long);                                  //add room for start/end address
   pMemBlock_Member = (far char *) _xalloc(&tempsz, 0, XALLOC_BB);
   if(pMemBlock_Member == NULL)
   {
      printf("\n _xalloc failed for MEMBER \n");
      //reboot
   }
   pStartAddrMark_Member = (far long *)pMemBlock_Member;
   pStopAddrMark_Member = (far long *)(pMemBlock_Member + tempsz - sizeof(long) );

   //check to see if the block is initialized (look for the beginning & ending marker)
   if ((*pStartAddrMark_Member != BLOCK_START_MEMBER) || (*pStopAddrMark_Member != BLOCK_END_MEMBER))
   {
      // zero the memory block
      _f_memset(pMemBlock_Member, 0, tempsz);

      Initialize with default data.
      InitializeWithDefaultData();
      // put markers at start and end of the memory block
      *pStartAddrMark_Member = BLOCK_START_MEMBER;
      *pStopAddrMark_Member = BLOCK_END_MEMBER;
   }
   PtrToFamilyMemberFile = (far Member_t *)(pMemBlock_Member + sizeof(long));


  while (1)
  {



   }

}