_uclose - Close Heap from Use

Syntax

#include <umalloc.h>
int _uclose(Heap_t heap);

uclose closes a heap when a process will not use it again. After you close a heap, any attempt in the current process to allocate or return memory to it will have undefined results. _uclose affects only the current process; if the heap is shared, other processes may still be able to access it.
Once you have closed the heap, use _udestroy to destroy it and return all its memory to the operating system.
Note: If the heap is shared, you must close it in all processes that share it before you destroy it, or undefined results will occur.

You cannot close The Developer's Toolkit run-time heap (_RUNTIME_HEAP).
For more information about creating and using heaps, see "Managing Memory" in the VisualAge C++ Programming Guide.

If successful, _uclose returns 0. A nonzero return value indicates failure. Passing _uclose a heap that is not valid results in undefined behavior.

The following example creates and opens a heap, and then performs operations on it. It then calls _uclose to close the heap before destroying it.

#define  INCL_DOSMEMMGR             /* Memory Manager values */
#include <os2.h>
#include <bsememf.h>                /* Get flags for memory management  */
#include <stdlib.h>
#include <stdio.h>
#include <umalloc.h>

int main(void)
{
   void    *initial_block;
   APIRET  rc;
   Heap_t  myheap;
   char    *p;

   /* Call DosAllocMem to get the initial block of memory */
   if (0 != (rc = DosAllocMem(&initial_block, 65536,
                              PAG_WRITE | PAG_READ | PAG_COMMIT))) {
      printf("DosAllocMem error: return code = %ld\n", rc);
      exit(EXIT_FAILURE);
   }
   /* Create a fixed size heap starting with the block declared earlier */
   if (NULL == (myheap = _ucreate(initial_block, 65536, _BLOCK_CLEAN,
                                  _HEAP_REGULAR, NULL, NULL))) {
      puts("_ucreate failed.");
      exit(EXIT_FAILURE);
   }
   if (0 != _uopen(myheap)) {
      puts("_uopen failed.");
      exit(EXIT_FAILURE);
   }
   p = _umalloc(myheap, 100);
   memset(p, 'x', 10);
   free(p);

   if (0 != _uclose(myheap)) {
      puts("_uclose failed");
      exit(EXIT_FAILURE);
   }
   if (0 != (rc = DosFreeMem(initial_block))) {
      printf("DosFreeMem error: return code = %ld\n", rc);
      exit(EXIT_FAILURE);
   }
   return 0;
}

uopen
udestroy
ucreate
Differentiating between Memory Management Functions
Managing Memory" in the VisualAge C++ Programming Guide

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