MALLOC(3X)           INTERACTIVE UNIX System           MALLOC(3X)



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

          SYNOPSIS
               #include <malloc.h>

               char *malloc (size)
               unsigned size;

               void free (ptr)
               char *ptr;

               char *realloc (ptr, size)
               char *ptr;
               unsigned size;

               char *calloc (nelem, elsize)
               unsigned nelem, elsize;

               int mallopt (cmd, value)
               int cmd, value;

               struct mallinfo mallinfo()

          DESCRIPTION
               The malloc and free functions provide a simple general-
               purpose memory allocation package, which runs considerably
               faster than the malloc(3C) package.  It is found in the
               library ``malloc'' and is loaded if the option ``-lmalloc''
               is used with cc(1) or ld(1).

               The malloc function 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.

               Undefined results will 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 will be unchanged up to the lesser of
               the new and old sizes.

               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.


          Rev. C Software Development Set                            Page 1

          MALLOC(3X)           INTERACTIVE UNIX System           MALLOC(3X)



               The available values for cmd are:

               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 24.

               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 mal-
                        loc, realloc, or calloc.  This option is provided
                        only for compatibility with the old version of mal-
                        loc 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.



          Rev. C Software Development Set                            Page 2

          MALLOC(3X)           INTERACTIVE UNIX System           MALLOC(3X)



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

          DIAGNOSTICS
               The malloc, realloc, and calloc functions return a NULL
               pointer if there is not enough available memory.  When real-
               loc 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.

          WARNINGS
               This package usually uses more data space than malloc(3C).
               The code size is also bigger than malloc(3C).
               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 dupli-
               cated.




































          Rev. C Software Development Set                            Page 3