Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### MSDBK

Prolog

Control Block Contents
MSDBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### MSDBK Prolog

     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.
     NOTES      : 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

#### MSDBK DSECT

    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

    *** 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

    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 V5R2.0. Last updated on 12 Apr 2006 at 17:05:52 EDT.
Copyright IBM Corporation, 1990, 2005