BRK(2)                  GENIX Programmer's Manual                  BRK(2)



      NAME
           brk, sbrk, break - change core allocation

      SYNOPSIS
           char *brk(addr)

           char *sbrk(incr)

      DESCRIPTION
           Brk sets the system's idea of the lowest location not  used  by  the
           program  (called the break) to addr (rounded up to the next multiple
           of 64 bytes on the PDP11, 512 bytes on SYS16, and 1024  bytes  on  a
           VAX-11).   Locations  not less than addr and below the stack pointer
           are not in the address space and will thus cause a memory  violation
           if accessed.

           In the alternate function sbrk, incr more bytes  are  added  to  the
           program's  data  space and a pointer to the start of the new area is
           returned.

           When a program begins execution via exec the break  is  set  at  the
           highest  location  defined  by  the  program and data storage areas.
           Ordinarily, therefore, only programs with growing data areas need to
           use break.

      SEE ALSO
           exec(2), vlimit(2), malloc(3), end(3)

      DIAGNOSTICS
           Zero is returned if the brk could be set; -1 if the program requests
           more  memory  than  the  system limit.  Sbrk returns -1 if the break
           could not be set.























      Printed 11/16/83                                                        1