malloc(3X)                (Specialized Libraries)                malloc(3X)


   NAME
         malloc, free, realloc, calloc, mallopt, mallinfo - memory allocator

   SYNOPSIS
         cc [flag ...] file ...  -lmalloc [library ...]

         #include <stdlib.h>

         void *malloc (size_t size)

         void free (void *ptr)

         void *realloc (void *ptr, size_t size)

         void *calloc (size_t nelem, size_t elsize)

         #include <malloc.h>

         int mallopt (int cmd, int value)

         struct mallinfo mallinfo (void)

   DESCRIPTION
         malloc and free provide a simple general-purpose memory allocation
         package.

         malloc returns a pointer to a block of at least size bytes suitably
         aligned for any use.

         The argument to free is a pointer to a block previously allocated by
         malloc; after free is performed this space is made available for
         further allocation, and its contents have been destroyed (but see
         mallopt below for a way to change this behavior).  If ptr is a null
         pointer, no action occurs.

         Undefined results occur if the space assigned by malloc is overrun or
         if some random number is handed to free.

         realloc changes the size of the block pointed to by ptr to size bytes
         and returns a pointer to the (possibly moved) block.  The contents
         are unchanged up to the lesser of the new and old sizes.  If ptr is a
         null pointer, realloc behaves like malloc for the specified size. If
         size is zero and ptr is not a null pointer, the object it points to
         is freed.

         calloc allocates space for an array of nelem elements of size elsize.
         The space is initialized to zeros.

         mallopt provides for control over the allocation algorithm.  The
         available values for cmd are:



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   malloc(3X)                (Specialized Libraries)                malloc(3X)


         M_MXFAST Set maxfast to value.  The algorithm allocates all blocks
                  below the size of maxfast in large groups and then doles
                  them out very quickly.  The default value for maxfast is 48.

         M_NLBLKS Set numlblks to value.  The above mentioned ``large groups''
                  each contain numlblks blocks. numlblks must be greater than
                  0.  The default value for numlblks is 100.

         M_GRAIN  Set grain to value.  The sizes of all blocks smaller than
                  maxfast are considered to be rounded up to the nearest
                  multiple of grain.  grain must be greater than 0.  The
                  default value of grain is the smallest number of bytes which
                  will allow alignment of any data type.  Value will be
                  rounded up to a multiple of the default when grain is set.

         M_KEEP   Preserve data in a freed block until the next malloc,
                  realloc, or calloc.  This option is provided only for
                  compatibility with the old version of malloc and is not
                  recommended.

         These values are defined in the malloc.h header file.

         mallopt may be called repeatedly, but may not be called after the
         first small block is allocated.

         mallinfo provides instrumentation describing space usage.  It returns
         the structure:

               struct mallinfo  {
                    int arena;      /* total space in arena */
                    int ordblks;    /* number of ordinary blocks */
                    int smblks;     /* number of small blocks */
                    int hblkhd;     /* space in holding block headers */
                    int hblks;      /* number of holding blocks */
                    int usmblks;    /* space in small blocks in use */
                    int fsmblks;    /* space in free small blocks */
                    int uordblks;   /* space in ordinary blocks in use */
                    int fordblks;   /* space in free ordinary blocks */
                    int keepcost;   /* space penalty if keep option */
                                    /* is used */
               }

         This structure is defined in the malloc.h header file.

         Each of the allocation routines returns a pointer to space suitably
         aligned (after possible pointer coercion) for storage of any type of
         object.

   SEE ALSO
         brk(2), malloc(3C).



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   malloc(3X)                (Specialized Libraries)                malloc(3X)


   DIAGNOSTICS
         malloc, realloc, and calloc return a NULL pointer if there is not
         enough available memory.  When realloc returns NULL, the block
         pointed to by ptr is left intact.  If mallopt is called after any
         allocation or if cmd or value are invalid, non-zero is returned.
         Otherwise, it returns zero.

   NOTES
         Note that unlike malloc(3C), this package does not preserve the
         contents of a block when it is freed, unless the M_KEEP option of
         mallopt is used.

         Undocumented features of malloc(3C) have not been duplicated.

         Function prototypes for malloc, realloc, calloc and free are also
         defined in the <malloc.h> header file for compatibility with old
         applications. New applications should include <stdlib.h> to access
         the prototypes for these functions.



































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