This example creates a heap to manage small amount of memory, and then frees it.

#define INCL_DOSMEMMGR
#define INCL_DOSERRORS
#include <os2.h>
#include <stdio.h>

#define NUMBLOCKS  128               /* Number of blocks in pool          */
#define POOLSIZE   (NUMBLOCKS*80+64) /* 128 blocks of 80 bytes each.  OS/2
                                        needs 64 bytes to manage the pool */
int main (VOID)
{
  PVOID   pvMemBase       = NULL;       /* Pointer to memory object (pool)*/
  PVOID   apvBlock[NUMBLOCKS] = {NULL}; /* Pointers to memory blocks      */
  ULONG   i               = 0;          /* A loop index                   */
  APIRET  rc              = NO_ERROR;   /* Return code                    */

    /* Allocate the memory pool.  Note the pool is intentionally NOT
       committed here.  OS/2 will commit the memory as needed.           */

  rc = DosAllocMem( &pvMemBase, POOLSIZE, PAG_WRITE );
  if (rc != NO_ERROR) {
    printf("DosAllocMem error:  return code = %u\n", rc);
    return 1;
  }
       /* Make the entire memory object available for Suballocation */

  rc = DosSubSetMem( pvMemBase, DOSSUB_INIT | DOSSUB_SPARSE_OBJ, POOLSIZE );
  if (rc != NO_ERROR) {
    printf("DosSubSetMem error:  return code = %u\n", rc);
    return 1;
  } else { printf("Memory object ready for suballocation.\n"); }

   /* Suballocate the pool into 128 memory blocks, each 80 bytes in size */

  for( i = 0; i < NUMBLOCKS; i++ ) {
    rc = DosSubAllocMem( pvMemBase, &apvBlock[ i ], 80 );
    if( rc != NO_ERROR ) {
      printf( "DosSubAllocMem error: return code = %u  (i = %u)\n", rc, i );
      break;             }
  }

                     /*    USE THE POOL HERE... */
             /* When done, free the 128 memory blocks */

  do {
    rc = DosSubFreeMem(  pvMemBase, apvBlock[ --i ], 80 );
    if (rc != NO_ERROR) {
      printf("DosSubFreeMem error:  return code = %u  (i = %u)\n", rc, i);
      return 1;
    }
  } while( i );

        /* Stop memory block management, and free the memory object */

  rc = DosSubUnsetMem( pvMemBase );
  if (rc != NO_ERROR) {
    printf("DosSubUnsetMem error:  return code = %u\n", rc);
    return 1;
  }

  rc = DosFreeMem( pvMemBase );
  if (rc != NO_ERROR) {
    printf("DosFreeMem error:  return code = %u\n", rc);
    return 1;
  } else {
    printf("Memory freed.\n");
  }

  return NO_ERROR;
}