MSDBK Back to Index page
 
Prolog 
Control Block Contents 
   MSDBK DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.


  MSDBK Prolog Top of page
 
 NAME       : HCPMSDBK
 DESCRIPTION: Monitor Send Block
 DSECT      : MSDBK
 FUNCTION   : To represent a monitor broadcast (IUCV Sends of the
              same information to one or more users).  The counts
              contained in an MSDBK are used to determine when the
              DCSS pages corresponding to that broadcast can be
              released for reuse.
     Data structure   Field location
     MNDI_EV_TOSEND   MNDI_EV_TOSEND_HEAD
                      MNDI_EV_TOSEND_TAIL
     MNDI_EV_SENT     MNDI_EV_SENT.MND_HEAD
                      MNDI_EV_SENT.MND_TAIL
     MNDI_SAM_SENT    MNDI_SAM_SENT.MND_HEAD
                      MNDI_SAM_SENT.MND_TAIL
 LOCATED BY :
 CREATED BY : HCPMOISS
              HCPMNXAE
 DELETED BY : HCPMOISR
              HCPMOIER
              HCPMOVPM
 REFERENCES : none
 SERIALIZED : The appropriate lock must be obtained for any
              manipulations to the list.
 RELOCATION CONSIDERATIONS : None
 COMPATIBILITY AND MIGRATION CONCERNS : The MSDBK is used to link Monitor broadcasts in
              a circular list.  As a result of this circular list
              implentation, it is a requirement that MSDFWDPT and
              MSDBCKPT are the first two words in the list.  This is
              necessary, because the code thinks that the head and
              tail pointers to the list are 'another element of the list'.
 
 
  MSDBK Control Block Content Top of page
 

 MSDBK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure MSDBK Monitor Send Block 0000 0 Address 4 MSDFWDPT Pointer to the next MDSBK on the list 0004 4 Address 4 MSDBCKPT Pointer to the previous MSDBK on the list 0008 8 Signed 4 MSD_SENT_CT Count of outstanding messages 000C 12 Signed 4 MSD_PEND_CT Count of pending messages 0010 16 Bitstring 4 MSD_TRGCL Target class of this message. This field fill be used to assign the TRGCLS parameter of the IUCV macro when sending data. 0014 20 Bitstring 8 MSD_CTL_ADDR (0) Control area addresses. This level exists so that the control area addressess remain together. It is necessary they be together because the data is used as the PRMMSG for the IUCV SEND. 0014 20 Address 4 MSD_CTLST_GRA Monitor control area starting address - guest real address 0018 24 Address 4 MSD_CTLEN_GRA Monitor control area ending address - guest real address 0000001C MSD$END * End of MSDBK 00000004 MSDSIZE (MSD$END-MSDBK+7)/8 MSDBK size in doublewords
 
 
  MSDBK Storage Layout Top of page
 
          
*** MSDBK - Monitor Send Block
*
*     +---------------------------+---------------------------+
*   0 |         MSDFWDPT          |         MSDBCKPT          |
*     +---------------------------+---------------------------+
*   8 |       MSD_SENT_CT         |       MSD_PEND_CT         |
*     +---------------------------+---------------------------+
*  10 |        MSD_TRGCL          |      MSD_CTLST_GRA        |
*     +---------------------------+---------------------------+
*  18 |      MSD_CTLEN_GRA        | 1C
*     +---------------------------+
*
*** MSDBK - Monitor Send Block
 
 
  MSDBK Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
MSD$END        0018 0000001C
MSD_CTL_ADDR   0014
MSD_CTLEN_GRA  0018
MSD_CTLST_GRA  0014
MSD_PEND_CT    000C
MSD_SENT_CT    0008
MSD_TRGCL      0010
MSDBCKPT       0004
MSDFWDPT       0000
MSDSIZE        0018 00000004
 
This information is based on z/VM 7.3.0 Last updated on 22 Jun 2022 at 15:52:55 EDT.
Copyright IBM Corporation, 1990, 2022