Generating an IOCDS
- Reads each statement from the input device.
- Prints each statement on the output printer.
- Checks the syntax of each statement
for correct format. If IOCP finds a syntax error (such as a missing
parenthesis), IOCP prints an error message on the output printer after
the statement containing the error. IOCP stops checking the syntax
of a statement when it encounters the first syntax error in that statement.
Therefore, if two or more syntax errors are in a single statement,
the second and following errors are found on subsequent runs of IOCP.
If IOCP finds an error in step 3, IOCP returns to step 1 and performs only steps 1-4 for the remainder of the statements.
- Checks the validity of each statement.
For example, IOCP checks that a CNTLUNIT statement has specified a
channel path that has been previously defined in a CHPID statement.
If an error is found, IOCP prints an error message on the output printer
after the statement containing the error.
If IOCP finds an error in step 4, IOCP returns to step 1 and performs only steps 1-4 for the remainder of the statements.
- Builds the appropriate identification,
channel path, control unit, or I/O device record and enters the record
into the IOCDS in storage.
If more statements remain to be read, IOCP returns to step 1.
After all the input statements have been processed and all the records have been entered into the IOCDS in storage, IOCP performs step 6.
- Generates the IOCDS and performs additional
checking. If IOCP finds an error, IOCP sends an error message and
then stops.
After IOCP has successfully generated an IOCDS, IOCP performs Step 7.
- Produces the IOCP configuration reports
of the IOCDS.
For z/OS and z/VSE: If requested (by a WRTCDS option other than NO), IOCP performs step 8.
For VM: If requested (by a generation option of the IOCP command other than NOWRTCDS), IOCP performs step 8.
- Writes the generated IOCDS to the
Support Element hard disk.
For z/OS: IOCP requires authorization before it writes an IOCDS. See Authorizing an IOCDS write.
For z/VM: The control program checks your privilege class. You must have privilege class C to write the IOCDS to the SE hard disk. You must have privilege class B to enable the IOCDS for dynamic I/O configuration changes.
For z/VSE: This step requires permission from the system operator (through message ICP050D) before IOCP writes to the SE hard disk.