LINC Programming Reference Manual - Public Support Login - Unisys

Introduction
CALL
For MCP based target hosts, using the BYFUNCTION; option with the CALL; command
gives you access to common user libraries that have been installed using the SL system
command. You do not have to embed the title of the library in the CALL; command that you
use to access the libraries. Instead, your user-defined System Library names (as used in SL
commands) can be used in the CALL; command, to identify the required library.
For each of the library programs you want to access in this way, you must code an
additional CALL; command that serves only to identify the library as called by function.
This command is required once within each LINC Subsystem in which there is a CALL;
command to a particular library, and once within each Report that calls that library.
The initialization code associated with the command is unconditionally executed.
Therefore, the Ispec or Global Logic containing the code does not need to be invoked to
begin execution. The Ispec or Global Logic does, however, need to be included as part of
your LINC System (or in a module of your LINC System).
Reasons for Using BYFUNCTION; Command Option
Reasons to use the BYFUNCTION; command option with the CALL; command are:
$ You do not need to embed the Library title, including pack name, in your logic.
$ You are not required to specify a usercode with the library name.
Using the BYFUNCTION; Command Option
In Reports, the BYFUNCTION; command option with the CALL; command is only valid in
Main Logic (Frame 00). The actual CALL; commands can be anywhere in Report logic.
If the command is included within your LINC Logic more than once (for example, because
of Inserted Global Logics), then the initialization will be generated for each occurrence.
Also, whenever a BYFUNCTION; command option is inserted, edited, or deleted,
(including LCOPY operations), all Subsystems of the LINC Specification are regenerated
when the LINC Specification is next generated.
This creates overhead; thus it is recommended that you place this command in a standard
location in your LINC Specification - for example, CLOSEDOWN Global Logic, where
accidental maintenance can be avoided or minimized.
Note: You must ensure that the libraries you call by function are first declared as
System Libraries by using the SL command. If this is not done on site, the
LINC program will be suspended, waiting for the library.
When you wish to make changes to the functions of an SL library, you should consult with
other users of the System Library, to prevent conflicting requirements.
v 1-57