Diagnosing VMCF/IUCV problems with the TSO MVPXDISP command

The TSO MVPXDISP command is used as a debugging aid to display the state of the connections from some address spaces to the VMCF address space. In addition, the command is used to obtain information about storage utilization for VMCF and IUCV-related buffers, as well as routines supporting the underlying PC functions. This information can be used by the IBM® Software Support Center to analyze the state of the VMCF address space.

The TSO MVPXDISP command is used to display information about a connection for a single user ID or started task to the VMCF address space, or all connections can be displayed. The command is also used to obtain information about the storage utilization. MVPXDISP must be an Authorized Program Facility (APF) command.

If you have a user application that is hung, issue the TSO MVPXDISP command and keep the output for help in diagnosing the problem.


>>-MVPXDISP--+--------+----------------------------------------><
             +-userid-+   
             '-ISAQ---'

userid: Specifies the name of a user ID or started task for which you want the information concerning the connection to the VMCF address space.
ISAQ: Specifies that you want information pertaining to storage utilization within the VMCF address space.

The parameters are optional. If no parameter is specified, information about all connections to the VMCF address space as well as the storage utilization data is displayed.

Figure 1 shows a sample of the output received from issuing the TSO MVPXDISP command with the userid parameter. The messages in this sample are only displayed if the PROFILE MSGID option is in effect for the TSO user ID.

Figure 1. MVPXDISP sample output using the userid parameter

mvpxdisp smtp
EZY2053I MVPXDISP: User SMTP     Asid 002C.                   ***** 
EZY2054I MVPXDISP: Data @ 15B20AD8 Sm=FF Cr0=000008E1 Flags=D4.     
EZY2055I MVPXDISP: Client of the VMCF address space.                
EZY2055I MVPXDISP: Client of SMSG.                                             
EZY2055I MVPXDISP: Client of VMCF.                                             
EZY2056I MVPXDISP:  IUCV mask=F8F8, Pending Ctl=0000, Appl=0000.               
EZY2057I MVPXDISP: VMCF: Buf=00182BA0, Len=00000118, Flgs=00 User=     Key= 80.
EZY2059I MVPXDISP: VMCF: Pending count=0 Flags=00000000.                       
EZY2058I MVPXDISP: IUCV: Connections=0, Max=255.                               
EZY2065I MVPXDISP: IUCV: Ctl flags=00000000 Appl flags=00000000. 
         
.  .  .  .
.  .  .  .

The output from the MVPXDISP command, when it is issued with the userid parameter, contains the following information:

User

User ID associated with the address space control block (ASCB) owning the connection to the VMCF address space.

Asid

Address space ID (ASID) for the user ID.

Data

Address of the control block containing extended information about the user ID.

Sm=

Saved system mask of the user's address space.

Cr0=

Control register 0 of the user's address space.

Flags

Control flags describing the state of the connection. The meaning of the flag bits is as follows:

X'80': SMSG is allowed.
X'40': User ID is a client of VMCF.
X'20': User ID is a client of IUCV.
X'10': User ID is a client of the VMCF address space.
X'08': Reserved.
X'04': User had the TRANSWAP field specified when initially made a client of VMCF.
X'02': Reserved.
X'01': Reserved.

Client of text string

Up to 4 lines of text that describe the settings of the bit fields from the Flags variable that concern the client status of the connection. Possible values for text string are:

VMCF address space
SMSG
VMCF
IUCV

IUCV mask=

Enable mask used with IUCV communications.

Pending Ctl=

Control pending interrupt mask used with IUCV communications.

Appl=

Application pending interrupt mask used with IUCV communications.

Buf=

Address of the VMCF user external interrupt buffer.

Len=

Length of the VMCF user external interrupt buffer.

Flgs=

Control flags associated with the VMCF connection. The meaning of the flag bits is as follows:

X'80': Specific AUTHORIZE was performed.
X'40': Priority messages are allowed.
X'20': Connection is in a quiesced state.
X'1F': Reserved.

User=

If a specific AUTHORIZE was performed, the name of the user ID with whom the restricted connection was established; otherwise, a blank field.

Key=

User key at the time the connection was initialized.

Pending count=

Count of pending VMCF requests that have been sent.

Flags=

Control flags associated with pending VMCF requests. Only byte 0 contains defined bit fields. All bit positions in bytes 1 through 3 are reserved. The meaning of the defined flag bits is as follows:

X'80': IRB is scheduled or running.
X'40': VMCF interrupt might be pending.
X'3F': Reserved.

Connections=

Count of active IUCV connections.

Max=

Maximum number of IUCV connections allowed.

Ctl flags=

Control flags associated with pending IUCV requests on the control path. Only byte 0 contains defined bit fields. All bit positions in bytes 1 though 3 are reserved. The meaning of the defined flag bits is as follows:

X'80': IRB is scheduled or running.
X'40': IUCV interrupt might be pending.
X'3F': Reserved.

Appl flags=

Control flags associated with pending IUCV requests on the application path. Only byte 0 contains defined bit fields. All bit positions in bytes 1 through 3 are reserved. The meaning of the defined flag bits is as follows:

X'80': IRB is scheduled or running.
X'40': IUCV interrupt might be pending.
X'3F': Reserved.

Figure 2 shows a sample of the output received from issuing the MVPXDISP command with the ISAQ parameter. The messages in this sample are only displayed if the PROFILE MSGID option is in effect for the TSO user ID.

Figure 2. MVPXDISP sample output using the ISAQ parameter

mvpxdisp isaq
EZY2060I MVPISAQ : VMCF_CVT VMCF_Dsa Header at 00B70F18    
EZY2061I MVPISAQ :  Subpool 231 1st Getmain count 1        
EZY2062I MVPISAQ :              2nd Getmain count 0        
EZY2063I MVPISAQ :  Frame size 1024 Max asked 1024(00000400)     
EZY2060I MVPISAQ : MVPXINF  XI_Dsa   Header at 15B13000          
EZY2061I MVPISAQ :  Subpool   0 1st Getmain count 1              
EZY2062I MVPISAQ :              2nd Getmain count 0              
EZY2063I MVPISAQ :  Frame size 8192 Max asked 8192(00002000)

The output from the MVPXDISP command, when it is issued with the ISAQ parameter contains the following information:

VMCF_Dsa Header at: Address of the anchor block for the dynamic storage areas used by the routines supporting the program call (PC) function.
XI_Dsa Header at: Address of the anchor block for the dynamic storage areas used by the VMCF address space while it services cross-memory calls.
Subpool: Subpool number from which the storage frames are allocated.
1st Getmain count: Count of the number of times a request was made for storage from the pool and none was available. It can be viewed as the maximum number of concurrent requests.
2nd Getmain count: Count of the number of times a storage request was made for an area that exceeded the frame size. This value should never by other than zero, since the frame sizes were chosen based on the maximum storage request size that should be made by the various routines.
Frame size: Number of bytes (decimal) allocated by a GETMAIN request.
Max asked: Largest area in bytes (decimal) that has been obtained from the storage pool to satisfy a request by the routines that exploit the storage pool.