HP 3000 Manuals HP 3000 Manuals
RULES FOR THE DL AREA
VPLUS/V makes use of the DL area for buffers and internal tables.
Therefore, if the DL area is put to any other use during the execution of
a VPLUS/V application, such use must not conflict with that of VPLUS/V.
To insure against conflict, observe the following rules:
1. The first use of the DL area by an application, including any
procedures, routines, or intrinsics executed on behalf of the
application, should be the call to VOPENFORMF that opens the forms
file and allocates the DL area needed by VPLUS/V.
2. The call to VCLOSEFORMF that frees up the DL area used by VPLUS/V
must not occur until the application has released all other DL
space allocated subsequent to the VOPENFORMF call.
These restrictions need not be followed if the application is wholly
coded in any combination of Pascal, HPFORTRAN 77, and HPBUSINESS BASIC
and sets the comarea item language to 5, which causes VPLUS/V to use the
heap procedures provided by Pascal instead of managing the DL area
directly.
VPLUS/V applications coded in other languages need to take great care if
they pass the language identifier of 5 as a means of getting around the
restrictions stated above. Specifying an incorrect language identifier
can cause other aspects of the VPLUS/V interface, such as addressing of
byte parameters, to function unreliably. In such a case, the application
must use the INTRINSIC mechanism (CALL INTRINSIC in COBOL) for the main
and all interacting parts of the application. Check the Pascal and COBOL
reference manuals for more information.
In all cases, check for any other use of the DL area by intrinsics such
as the DSG intrinsics.