Guardian Application Conversion Guide

Handling the Message System Interface
Converting Other Parts of an Application
096047 Tandem Computers Incorporated 8–41
Handling the Message
System Interface
Prior to the D-series versions of the operating system, the RESERVELCBS procedure
allowed you to reserve link control blocks (LCBs) for sending and receiving messages.
It also performed certain secondary functions concerning the limits on the number of
extended memory link control blocks (XLBs).
Under the D-series versions of the operating system, RESERVELCBS performs no
function but can still be used without error. Reserving link control blocks is no longer
applicable, and the secondary functions of the procedure can be accomplished by
calling CONTROLMESSAGESYSTEM.
If your existing program calls RESERVELCBS specifically to reserve LCBs, then you
can safely remove the call. Such calls typically specify a number of LCBs significantly
greater than 1. For example, the following call reserves 20 receive LCBs and 20 send
LCBs:
CALL RESERVELCBS(20, !receive LCBs
20); !send LCBs
If your existing program calls RESERVELCBS to raise the limit on the number of XLBs,
then you should convert your program to use the CONTROLMESSAGESYSTEM
procedure. For such programs, the default limit of 255 XLBs for receive XLBs or 1023
for send XLBs was considered inadequate. Programs typically remove the limit by
specifying a 1 for the number of send or receive LCBs. For example, your existing
program might remove the limit on receive XLBs as follows:
CALL RESERVELCBS(1, !receive LCBs
0); !send LCBs
Replace this call to RESERVELCBS with a call to the CONTROLMESSAGESYSTEM
procedure. Choose a value for the limit on XLBs that is suitable for your application.
A typical value might be 2000:
LITERAL receive^xlbs^limit = 0;
...
value := 2000;
CALL CONTROLMESSAGESYSTEM(receive^xlbs^limit,
value);