BREAK(II) 8/5/73 BREAK(II)
NAME
break - set program break
SYNOPSIS
(break = 17.)
sys break; addr
char *sbrk(incr)
DESCRIPTION
Break sets the system's idea of the lowest location not used
by the program to addr (rounded up to the next multiple of
64 bytes). 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.
From C, the calling sequence is different; 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(II)
DIAGNOSTICS
The c-bit is set if the program requests more memory than
the system limit (currently 20K words), or if more than 8
segmentation registers would be required to implement the
break. From C, -1 is returned for these errors.