IOCP command – usage notes for VM

This topic lists some notes to keep in mind when you use the IOCP command.

Notes:

Beginning with Version 6 of IOCP ( APAR VM66549), you must issue the IOCP command in the z/CMS environment. If you do not, the following message results:
```
DMSICP340E IOCP requires z/CMS to run - exiting. IPL ZCMS and try again      
         
```
Beginning with CP APAR VM66423 released in conjunction with IOCP Version 6 Release 1.2, if you specify the deprecated IOCP CMS utility option DYN or NODYN, the following message results:
```
Parameters DYN/NODYN are deprecated and ignored
```
You must have the correct privilege class. The control program checks your privilege class when IOCP attempts to read or write an IOCDS. You must have privilege class C to read or write an IOCDS; you must also have privilege class C to avoid IOCP warning message ICP068I when performing a deck verification (option NOWRTCDS). You must have privilege class B to enable dynamic I/O configuration capability; otherwise, IOCP informational message ICP071I results.
If you try to read from an IOCDS or write an IOCDS and you do not have the privilege class C, you receive the following messages:
```
ICP402I  IOCP RECEIVED AN UNEXPECTED RESPONSE CODE OF 01F0 HEX
          ATTEMPTING READ OR WRITE OF AN IOCDS
 
ICP051I  IOCP VERSION nn.nn.nnn TERMINATED. CODE=xx 
```
Note: You can also receive the previous messages if you try to read or write an IOCDS when another user is reading or writing an IOCDS. The messages are printed on the SYSPRINT device. IOCP then stops processing.
If you try to read or write an IOCDS or perform a deck verification (option NOWRTCDS) and you do not have the privilege class C, you receive the following message:
```
ICP068I **WARNING** IOCP WAS UNABLE TO DETERMINE IF THE CONFIGURATION          
         IS USABLE ON THE EC LEVEL OF THIS PROCESSOR (CODE 01F00000)
```
If you do not have privilege class B, your I/O configuration will not be enabled for dynamic and you receive the following informational message from IOCP:
```
ICP071I IOCP GENERATED A DYNAMIC TOKEN HOWEVER DYNAMIC I/O 
        CHANGES ARE NOT PERMITTED WITH THIS IOCDS. 
```

For z/VM® 4.4.0 and prior releases, if you do not have CP APAR VM63426 installed, you receive the following message:

 ICP068I **WARNING** IOCP WAS UNABLE TO DETERMINE IF THE CONFIGURATION
           IS USABLE ON THE EC LEVEL OF THIS PROCESSOR (CODE 40F00000)

You receive the following error messages and IOCP processing stops if you try to update an IOCDS or request a configuration report for an IOCDS while IOCP is running on a CPC that does not require the version of IOCP described in this publication:
```
ICP400I  READ/WRITE OF IOCDS IS INVALID ON THIS PROCESSOR (nnnn) 

ICP051I  IOCP VERSION nn.nn.nnn TERMINATED. CODE=xx
```
If you and another user attempt to read the same IOCDS at the same time, or if you and another user attempt to write the same IOCDS at the same time, you or the other user receive the following messages:
```
ICP405I  IOCP RECEIVED AN UNEXPECTED RETURN CODE OF 09 OR 65
                  HEX ATTEMPTING READ OR WRITE OF AN IOCDS
 
ICP051I  IOCP VERSION nn.nn.nnn TERMINATED. CODE=xx
```
Wait several minutes and again attempt to read or write that IOCDS by issuing another IOCP command.
You must define your I/O configuration for the CPC using IOCP statements. When you perform an initial program load (IPL) of VM, VM creates its software I/O configuration by sensing the devices in the hardware I/O configuration. If all the devices return all of the information VM needs, VM completes its software I/O configuration. If not, you must specify this information in the system configuration file.
If you try to write an IOCDS and either the IOCP abnormally ends or you issue the CMS command HALT EXECUTION (HX) while IOCP is running, you prevent another authorized user from using an IOCDS. Under these circumstances, the system might have locked the IOCDS for you. If the other user tries to write to any IOCDS, the following messages are sent:
```
ICP401I  READ/WRITE IOCDS FACILITY TEMPORARILY BUSY (RC=4). RETRY LATER
 
ICP051I  IOCP VERSION nn.nn.nnn TERMINATED. CODE=xx
```
The xx is a code that indicates IOCP encountered an error while trying to write the locked IOCDS.
If the other user attempts to read the IOCDS that has been locked, the following messages are displayed to that user:
```
ICP403I  LEVEL Ax IOCDS IS INVALID 

ICP051I  IOCP VERSION nn.nn.nnn TERMINATED. CODE=xx
```
The xx is a code that indicates IOCP encountered an error while trying to read the locked IOCDS.
These messages are sent each time the other user tries to run IOCP until you do one of the following:
- Rerun IOCP to completion, successfully writing the locked IOCDS to the Support Element.
- Send a SYSTEM RESET command to reset your virtual machine.
- Send a LOGOFF command to log off your virtual machine.
The other user can then access any of the IOCDSs.