IOSCHECK subcommand — format I/O supervisor data

Use the IOSCHECK subcommand to format the contents of specific I/O supervisor (IOS) control blocks and related diagnostic information.

You request diagnostic information about a captured unit control block (UCB) with the CAPTURE parameter on IOSCHECK. IOSCHECK produces different diagnostic reports for captured UCBs with the address space selection parameter(s) (ALL, CURRENT, ERROR, TCBERROR, ASIDLIST, and JOBLIST).

Address Space Selection Parameters
- ALL processes all address spaces.
- CURRENT processes active address spaces of the dump.
- ERROR processes any address space with an error indicator or containing a task with an error indicator.
- TCBERROR processes any address space containing a task with an error indicator.
- ASIDLIST processes address spaces associated with ASID(s).
- JOBLIST or JOBNAME processes address spaces associated with job names.
If you do not specify an address space selection parameter, CURRENT is the default. Address space selection parameters only apply with the CAPTURE parameter.

Syntax

   { IOSCHECK } [ ACTVUCBS ]
   { IOSK     }
                [ ALLUCBS ]
                [ CAPTURE ]
                [ CHAR(device-number-list) ]
                [ CHPR ]
                [ COMM(device-number-list) ]
                [ CTC(device-number-list) ]
                [ DASD(device-number-list) ]
                [ DISP(device-number-list) ]
                [ EXCEPTION ]
                [ HOTIO ]
                [ MIH ]
                [ RECOVERY ]
                [ SMGRBLKS ]
                [ TAPE(device-number-list) ]
                [ UCB(device-number-list) ]
                [ UREC(device-number-list) ]
                [ VALIDATE ]

-------- Address Space Selection Parameters ----------------

                [ ALL ]
                [ CURRENT ]
                [ ERROR ]
                [ TCBERROR ]
                [ ASIDLIST(asidlist) ]
                [ JOBLIST(joblist)|JOBNAME(joblist) ]

-------- SETDEF-Defined Parameters -------------------------
Note: You can override the following SETDEF parameters.
See SETDEF subcommand — set defaults.

                [ ACTIVE | MAIN | STORAGE          ]
                [ DSNAME(dsname) | DATASET(dsname) ]
                [ FILE(ddname) | DDNAME(ddname)    ]
                [ PATH(path-name)     ]
                [ PRINT | NOPRINT ]
                [ TERMINAL | NOTERMINAL ]
                [ TEST | NOTEST ]

Parameters
In the parameters, device-number-list is one of the following:
- A single hexadecimal device number of up to four digits.
  - Parentheses are accepted but are not required.
  - Leading zero digits are accepted but are not required.
- A range of device numbers defined by the lowest and highest device numbers separated by a colon.
  - Parentheses are accepted but are not required.
  - Leading zeros are accepted but are not required.
  - The second device number must be equal to or greater than the first, for example, 193:198.
- A list containing either single device numbers or ranges of device numbers. Parentheses are required. In the list, separate list members with blanks, commas, or horizontal tabulation (X'05') characters. The separators are permitted, but not required, between the left parenthesis and the first member and between the last member and the right parenthesis.
Report Type Parameters
Use these parameters to select the type of report.
ACTVUCBS
Validates I/O control blocks, formats active UCBs and these associated control blocks:
- IOQ
- IOSB
- SRB
- EWA
- CRWQ
- SRWQ
ALLUCBS
Validates the I/O control blocks and formats all UCBs, along with these associated control blocks:
- IOQ
- IOSB
- SRB
- EWA
- CRWQ
- SRWQ
CAPTURE
Formats the captured UCB pages in an address space (based on the address space selection parameters) along with these associated control blocks:
- IOQ
- IOSB
- SRB
- EWA
- CRWQ
- SRWQ
An application program can access an above 16 megabyte UCB with a 24-bit address through a view of the UCB captured in the program's address space.
The report also displays the captured UCB pages in common storage, if any exist. The report gives you the address space identifier (ASID) and information about each captured page. The report provides the following information for each captured page:
Actual page address

Captured page address

Captured UCB count
The captured UCB count is the number of captures of UCBs, these can be captures of the same UCB.
CHAR(device-number-list)

Requests formatting of selected channel-to-channel attention routine (CHAR) UCBs.

CHPR

Requests formatting of the installation channel path table (ICHPT), the channel recovery block (CHRB), and the global channel report word queue (CRWQ) elements.

COMM(device-number-list)

Requests formatting of selected communication (COMM) UCBs.

CTC(device-number-list)

Requests formatting of selected channel-to-channel (CTC) UCBs.

DASD(device-number-list)

Requests formatting of selected direct access storage device (DASD) UCBs.

DISP(device-number-list)

Requests formatting of any dispatcher (DISP) UCBs that you have selected (using device-number-list).

EXCEPTION
Specifies that IPCS check the validity of the IOS control blocks and print diagnostic error messages for blocks that are not valid. This parameter formats these control blocks:
- I/O communications area (IOCOM)
- I/O communications writeable area (IOCW)
- IOS level definitions
- I/O work area (IOWA) for each processor, and the IOS module work areas for each IOWA
- I/O prevention table (IOPT), if accessible
EXCEPTION is the default.

For additional information about IOS level definitions see z/OS MVS Diagnosis: Reference.
HOTIO

Requests formatting of the hot I/O detection table (HIDT) and the associated status collector data areas (SCDs).

MIH

Requests formatting of the missing interrupt handler work area (MIHA) and the associated time interval control blocks (TICBs).

RECOVERY

Requests formatting of the control blocks for the HOTIO, MIH, and CHPR parameters.

SMGRBLKS
Requests formatting of entries in the IOS storage manager page table for IOQ, RQE, and large blocks, and formatting of the queue of pages for each entry. The string LGA will appear in the formatted output instead of LGE to distinguish between a below the line large block and above the line large block.
```
SMGR: 0188CB70                                                              
    +0000  BLKID.... LGEB      PGID..... LGAPOOL IOS SMGR                  
    +0014  PGESZE... 00001000  PGFLG1... 00        PGFLG2... 00            
    +001A  PGPOOL... 00E2      SYNCA.... 0188C1D0  BLKCNT... 000F          
    +0022  TBLKLN... 0100      BLKLEN... 00F8      POFSET... 0100          
    +0028  PTOLE.... 0002      LINKOF... 00F4      HDROF.... 00F8          
    +002E  BIDOF.... 00F0      PGEINC... 0001000F  ALLOCW... 00000076      
    ...  
                                                                           
 PAGE: 02FCC000                                                              
    +0000  RCNT..... 0000000F  BLKP..... 00FCC100  FLG1..... 80            
    +0009  FLG2..... 00        MCNT..... 000F      CHN...... 02FCB000      
    +0010  ID....... LGAPOOL IOS SMGR              WKAR..... 00000000      
    +0024  EXTP.....           BACK..... 00000000                            
                                                                             
LGAB at 01FCC100                                                             
    +0000  00000000  C5E7D7D9  00FCBF68  00000000  | ....EXPR........
    +0010  00000000  00000000  00000000  00000000  | ................     
    +0020  00000000  00000000  00000000  00000000  | ................      
    ... 
```
TAPE(device-number-list)

Requests formatting of selected TAPE UCBs and ranges.

UCB(device-number-list)

Requests formatting of selected unit control blocks (UCBs).

UREC(device-number-list)

Requests formatting of selected unit record (UREC) UCBs.

VALIDATE
Requests validity checking of the following IOS control blocks:
- Device class queue chain (DCQ)
- Unit control blocks (UCB) queued off the DCQ
- I/O request blocks (IOQ) chained off the UCB and the associated IOQ chain
- I/O supervisor block (IOSB) pointed to from each IOQ
- Service request block (SRB) pointed to from each IOSB
- IOS error recovery procedure (ERP) work area (EWA) pointed to from the IOSB
When IOS detects a control block that is not valid, IOS formats the control block, and prints a diagnostic error message.
Note: For SVC dumps, not all the data pertaining to IOSCHECK is saved at the time of error. As a consequence, many control blocks may be reused before the data is dumped. Informational messages indicate that the data is not from the time of error. For example, the following message indicates that the IOQ has been reused:
IOS10107I IOQ AT xxxxxxxx does not point to UCB at yyyyyyyy
Address Space Selection Parameters
Use these parameters to obtain captured page data from particular address spaces, which you specify by their ASIDs. These parameters only apply with the CAPTURE parameter. If you specify CAPTURE but omit these parameters, the default is CURRENT. For more information, see the select ASID service in z/OS MVS IPCS Customization.
ALL

Specifies processing of captured pages for all address spaces in the system at the time the dump is generated.

CURRENT

Specifies processing of captured pages for each address space that is active (for example, dispatched on some central processor) when the dump is generated.

ERROR

Specifies processing of captured pages for any address space with an MVS™ error indicator or containing a task with an error indicator.

TCBERROR

Specifies processing of captured pages for any address space containing a task with an error indicator. Blocks for address spaces with an error indicator are not processed.

ASIDLIST(asidlist)

Specifies a list of ASIDs for the address spaces to be in the report.
The asidlist can be a single ASID, a range of ASIDs, or a list of noncontiguous ASIDs. When you specify a range, separate the first and last ASIDs in the range with a colon. When you specify a list, separate the list members with commas.

The ASID can be 1 through 65535. An ASID can be expressed using the notation X'nnn', F'nnn', or B'nnn'. An unqualified number is assumed to be fixed.

This subcommand does not process summary dump records (ASID X'FFFA').

JOBLIST(joblist) or JOBNAME(joblist)

Specifies a list of job names whose associated address spaces are to be in the report. Use commas to separate the job names in the list; do not enclose job names in apostrophes; and do not specify a range of job names.
Return codes
See Standard subcommand return codes for a description of the return codes produced by the IOSCHECK subcommand.
Example 1: Display IOS-related control blocks.
- Action
```
COMMAND ===> IOSCHECK UCB(2D0,2E0,410:440,620)
```
- Result
  This example formats UCBs for 3 device numbers and one range. For an example of IOSCHECK output, see the IOS component in z/OS MVS Diagnosis: Reference.

Example 2: Display captured UCB information for address spaces that are active.

Action
```
COMMAND ===> IOSCHECK CAPTURE
```

Result

This example formats the captured UCB information for any address space that is active. The output looks similar to the following for each address space:

                      * * * ADDRESS SPACE CAPTURE DATA * * *

    ASID 000F

                      ACTUAL        CAPTURE       CAPTURE
                      PAGE ADDRESS  PAGE ADDRESS  UCB COUNT
                      ------------  ------------  ------------

                      01D0E000      006F8000      00000005

                      01D0F000      006F7000      00000003

Two pages were captured in address space 000F. The first page had five captures of UCBs and the second had three.