FYI....  Declaring an initial value in a DATA statement in
FORTRAN essentially causes the variable to be 'static', known
only to the routine declaring it.  For subroutines, this has
the affect of having the address of the variable located
in DB-relative and not Q-relative. Also, the variable is not
'reinitialized' on every call to the subroutine as the DATA
statement initialization only occurs once at initial load/run
of the program following the resolution of the links.  However,
knowing this can also save stack space as sometimes programmers
did this all the time and thus consumed large amounts of the
DB-portion of the stack when it wasn't really necessary.

In COBOL, a subprogram by default is DYNAMIC, which essentially
causes the data items to be declared Q-relative and thus not
retain their values between calls. However, if one declares the
routine as NON-DYNAMIC, the declared variables become DB-relative
and will retain their value between calls. This is outlined in
Ch 11 in the COBOL II reference manual.


At 10:23 AM 12/17/01 -0800, David T Darnell wrote:
>This sounds like it works the same as the FORTRAN "COMMON" declaration.
>There is another method for making a variable "static", which is:
>
>       INTEGER IVAR
>       SAVE IVAR
>
>The above doesn't make IVAR available to other programs or subroutines, it
>just allocates it as static, so that the next time the subroutine is
>entered, the value is the same as the last time the subroutine was exited.
>
>Variables (once defined) can be added to a COMMON declaration, which can
>be named or not. then, the same memory locations are available to all
>subprograms in the same instance of a program, but are not shared among
>multiple instances of the program (i.e. different sessions). On the
>HP1000, we also had SYSTEM COMMON which would allow multiple programs
>whether or not in different sessions to share the same memory locations.
>
>-dtd
>
>
>
>
>
>
>
>[log in to unmask] on 12/17/2001 09:51:00 AM
>To:     [log in to unmask]@Internet
>cc:      (bcc: David T Darnell/CO/KAIPERM)
>Subject:        Re: [HP3000-L] Retention of switch value in called program
>
>Another approach I have used successfully from time to time is to declare
>data items as EXTERNAL.
>
>This is a feature of COBOL-85 and beyond so the appropriate $CONTROL and
>compiler entry point must be used.
>
>Basically, EXTERNAL creates a region outside your program which is shared
>among and between the main program and subroutines without using the USING
>clause.
>
>Each routine may change the area as it sees fit and the data remains as it
>was last changed.
>
>You could also do this with data records because EXTERNAL can also be used
>for files as well as the WORKING-STORAGE SECTION.
>
>This works whether the subroutines are called statically or dynamically.
>
>* To join/leave the list, search archives, change list settings, *
>* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
>
>* To join/leave the list, search archives, change list settings, *
>* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *

* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *