GDSX Manual

Design and Development
Extended General Device Support (GDSX) Manual–134303
2-2
Using D-Series Features
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Pathway/TS configurations, if applicable
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Whether static or dynamic SUs will be used
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Fully specify requirements for the proposed GDSX process, including:
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Different types of tasks that are required. Normally there are two different
types, DEVICE^HANDLER tasks and LINE^HANDLER tasks. However, by
means of the term^type parameter (which may be determined by the SCF ADD
command’s SUTYPE attribute) passed to DEVICE^HANDLER tasks, you can
effectively create different types of DEVICE^HANDLER tasks by executing
different subsets of code within the DEVICE^HANDLER procedure.
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Which user exits will be customized, and which exits will be stubs (see
Section 9, “User Exit Descriptions,” for information on user exits).
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Information that needs to be shared among tasks. Because multiple copies of a
USCODE procedure can be running at the same time in a multithreaded GDSX
environment, USCODE variables must be defined properly. If the value of a
variable is unique for each task at run time, declare the variable as a local
variable. If a variable must be shared among tasks, declare the variable as a
global. For read-only globals, the shared extended pool (see "Memory Pools"
on page 2-23) can be used. In order to properly update globals, semaphore
control may be necessary (see "Semaphore Control" on page 2-38).
Typically, user code has global data blocks, such as common^data and
user^private—see the example listings in Appendix B. Global data within the
common^data block can be referenced and updated by both TSCODE and
USCODE, while global data within the user^private data block can be
referenced and updated only by USCODE tasks.
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Which memory pools will be used, and what memory pool record structures will
be. See "Memory Pools" on page 2-23.
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Special memory requirements.
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Which files will be opened privately and which will be opened publicly. See the
considerations for ^OPEN and ^FILE_OPEN_ in "Service Routines" on page
8-1.
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Level of fault tolerance required for each user task in the GDSX process. Weigh
the need for fault tolerance against the overhead incurred with all three levels of
processing. See "Fault Tolerance" on page 2-27.
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Whether to use the NonStop TM/MP product in USCODE to protect
transactions.
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Specify any necessary access method control details.
Using D-Series Features
A converted application is one that has been modified to use some extended feature of
the D-series operating system. An unconverted application uses no extended features of
the D-series operating system. TSCODE assumes that USCODE is converted if and