BRK(2)                                                     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 a PDP11 and 1024 bytes on a
          VAX).  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.  (Rounding occurs as with brk, but a
          nominal break is remembered, so rounding does not accumu-
          late.)

          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), 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 or if too many
          segmentation registers would be required to implement the
          break.  Sbrk returns -1 if the break could not be set.