Subsystem Control Point (SCP) Management Programming Manual

Communicating With an SCP Process
Subsystem Control Point (SCP) Management Programming Manual—520619-001
2-11
Creating a High-PIN SCP Process
Creating a High-PIN SCP Process
The SCP program has the HIGHPIN object-file attribute set to OFF so processes
generated from it always run at a low PIN (a process identification number less than
255). However, you can reset the HIGHPIN attribute to ON and create high-PIN SCP
processes by issuing these Binder commands:
add * from old-scp-object-file-name
set highpin on
build new-scp-object-file-name
Be sure to set the license and PROGID for the new SCP object file.
Once the HIGHPIN object-file attribute is set to ON, you can create a high-PIN SCP
process using the HIGHPIN process option of the RUN command or the
PROCESS_CREATE_ procedure create-options parameter, as described on 2-9
.
For considerations relating to the interaction of high-PIN and low-PIN processes in a
network, see Interprocess Communications Restrictions
on page 3-9.
Selecting a LOG File
The SCP process uses the log file specified in the LOG or LOGFILE startup parameter,
or the file specified in the most recent ALTER command. Regardless of how you
specify it, consider these points when selecting a log file:
•
Do not use a terminal as the logging file unless special circumstances require it.
Logging uses waited I/O operations, and terminals are frequently unavailable due to
manual input operations. This can adversely affect SCP process performance. A
terminal might be an appropriate log file in testing and debugging environments but
usually is not in production environments.
•
Using a printer as the log file brings the same concerns. Printers can become not-
ready, and the resulting interruption of logging activity can severely impact
performance.
•
Using a spooling process as the log file lets the resulting files be examined online
using the PERUSE program or printed after an ALTER command switches logging
to another file.
•
The use of a disk file as the logging file is the most common choice. Specifying a
disk file as the log file assumes that the file already exists. The types of operations
performed on such files preclude the use of an edit file. Typically, an entry-
sequenced file with a record size of at least 132 bytes is adequate for log output.
You can create such a file with the File Utility Program (FUP):
FUP CREATE filename,TYPE E,REC 132, EXT (pri,sec)
•
If you inhibit logging (by omitting the LOG parameter or its filename argument),
emergency output—output that precedes the abnormal termination of the process—
is sent to the home terminal.
•
If the specified logging file cannot be accessed, the process does not start.