BUILD ATTACH (MRO)

Specify values for an MRO attach header.

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BUILD ATTACH (MRO)

>>-BUILD ATTACH--ATTACHID(name)--+---------------+-------------->
                                 '-PROCESS(name)-'   

>--+----------------+--+----------------+----------------------->
   '-RESOURCE(name)-'  '-RPROCESS(name)-'   

>--+-----------------+--+-------------+------------------------->
   '-RRESOURCE(name)-'  '-QUEUE(name)-'   

>--+--------------------+--+---------------------+-------------->
   '-IUTYPE(data-value)-'  '-DATASTR(data-value)-'   

>--+-------------------+---------------------------------------><
   '-RECFM(data-value)-'   

Description

BUILD ATTACH (MRO) specifies a set of values to be placed in the named attach header control block. This control block contains values that are to be sent in an MRO attach FMH (Function Management Header) that is constructed by CICS®, and is sent only when a SEND ATTACHID or CONVERSE ATTACHID command is executed. The specified values override existing values in the control block; unspecified values are set to default values.

For more information about MRO and IRC, see the Introduction to CICS intercommunication .

Options

ATTACHID(name)
specifies that the set of values is to be placed in an attach header control block identified by the specified name (1–8 characters).
DATASTR(data-value)
corresponds to the data stream profile field, ATTDSP, in an LUTYPE6.1 attach FMH.

For communication between two CICS systems, no particular significance is attached by CICS to the data stream profile field in an attach FMH. For most CICS applications, the option can be omitted.

The “data-value” is a binary halfword. Only the low-order byte is used. The SNA-defined meanings of the bits are as follows:
0–7    reserved - must be set to zero
8-11   0000 - user-defined
       1111 - SCS data stream
       1110 - 3270 data stream
       1101 - structured field
       1100 - logical record management
12-15  defined by the user if bits 8-11
       are set to 0000; otherwise reserved
       (must be set to zero)

A value of “structured field” indicates that chains begin with four bytes of data that are used to interpret the following data; overall length (2 bytes), class identifier (1 byte), and subclass identifier (1 byte). A value of “logical record management” indicates that chains can be split into separate fields by the data receiver.

If the option is omitted, a value of “user-defined” is assumed.

IUTYPE(data-value)
corresponds to the interchange unit field, ATTIU, in an LUTYPE6.1 attach FMH.
The “data-value” is a halfword binary. Only the low-order 7 bits are used. The SNA-defined meanings of the bits are as follows:
0–10   reserved - must be set to zero
11     0 - not end of multichain interchange unit
       1 - end of multichain interchange unit
12,13  reserved - must be set to zero
14,15  00 - multichain interchange unit
       01 - single chain interchange unit
       10 - reserved
       11 - reserved

If the option is omitted, values of “not end of multichain interchange unit” and “multichain interchange unit” are assumed.

PROCESS(name)
corresponds to the process name, ATTDPN, in an LUTYPE6.1 attach FMH.

For communication between two CICS systems, a transaction running in one system can acquire a session to the second system and can identify the transaction to be attached; in the second system the identification is carried in the first chain of data sent across the session. In general, the first four bytes of data identify the transaction to be attached. However an attach FMH, identifying the transaction to be attached, can be built and sent; the PROCESS option is used to specify the transaction name. (Note that the receiving CICS system uses just the first four bytes of the process name as a transaction name.)

No significance is attached by CICS to process names in attach FMHs sent in chains of data other than the first.

For communication between a CICS system and another subsystem, refer to documentation supplied by the subsystem about how to use the process name field in an attach FMH.

QUEUE(name)
corresponds to the queue name, ATTDQN, in an attach FMH.

For communication between two CICS systems, no significance is attached by CICS to the queue name in an attach FMH.

For communication between a CICS system and another subsystem, refer to documentation supplied by the subsystem about how to use the queue name field in an attach FMH.

RECFM(data-value)
corresponds to the deblocking algorithm field, ATTDBA, in an LUTYPE6.1 attach FMH.

For communication between two CICS systems, no particular significance is attached by CICS to the deblocking algorithm field in an attach FMH. For most CICS applications, the option can be omitted.

The “data-value” is a halfword binary value. Only the low-order 8 bits are used. The SNA-defined meanings of the bits are as follows:
0–7   reserved - must be set to zero
8-15  X'00' - reserved
      X'01' - variable-length
              variable-blocked
      X'02' - reserved
      X'03' - reserved
      X'04' - chain of RUs
      X'05' to X'FF' - reserved

If the option is omitted, a value of “chain of RUs” is assumed.

RESOURCE(name)
corresponds to the resource-name, ATTPRN, in an LUTYPE6.1 attach FMH.
RPROCESS(name)
corresponds to the return-process name, ATTRDPN, in an LUTYPE6.1 attach FMH.

For communication between two CICS systems, no significance is attached by CICS to the return-process name in an attach FMH.

For communication between a CICS system and another subsystem, refer to documentation supplied by the subsystem about how to use the return-process name field in an attach FMH.

RRESOURCE(name)
corresponds to the return-resource name, ATTRPRN, in an LUTYPE6.1 attach FMH.

For communication between two CICS systems, no significance is attached by CICS to the return-resource name in an attach FMH.

For communication between a CICS system and another subsystem, refer to documentation supplied by the subsystem about how to use the return-resource name field in an attach FMH.



dfhp4_buildattachmro.html | Timestamp icon Last updated: Thursday, 27 June 2019