IMS as primary half session

A specific bind format is sent by IMS during an IMS-to-other session initiation. If the mode table entry indicates negotiated bind, IMS overrides the mode table primary NAU protocol field with the indicated values prior to sending the bind.

IMS allows some parameters to be optionally set by a VTAM® mode table entry or negotiated bind response. IMS then operates within the indicated constraints. For a non-negotiated bind, IMS checks the parameters for validity before sending the bind. For negotiated bind, IMS checks the parameters for validity prior to sending the BIND request and upon receipt of the bind response, because the secondary half session can modify parameters within the constraints indicated in the following table.

Table 1. Logical unit type 6.1 bind parameters
Byte Bit Content BIND FORMAT description1
0   X'31' Bind request code
1 0-3 B'0000' FORMAT: TYPE 0
  4-7 B'0000', B'0001'

BIND TYPE:
0000 - negotiated
0001 - non-negotiated
2 0-7 X'12' FM Profile 18
3 0-7 X'04' TS Profile 4
4     Primary NAU protocol
0 B'1' Multiple RU chains
1 B'0' Immediate request
2-3

B'10', B'11'
(B'11' set for
negotiated BIND)

 10-Definite response chains

11-Exception/Definite response chains
4 B'0' Cannot send prepare
5 B'0' Reserved
6 B'0' No compression
7 B'1' 0-Primary cannot end bracket

1-Primary can send end bracket
5     Secondary NAU protocol
0 B'1' 0-Single RU chains, 1-Multiple RU chains
1 B'0' Immediate request
    01-Exception response chains
    10-Definite response chains
2-3 B'10', B'11' 11-Exception/Definite response chains
4 B'0' Cannot send prepare
5 B'0' Reserved
6 B'0' No compression
    0-Secondary cannot end bracket
7 B'0', B'1' 1-Secondary can send end bracket
6     Common NAU protocol
0 B'0' Reserved
1 B'1' Function management headers allowed
    Bracket state
    0 - Bracket state mgr reset to in-bracket state
2 B'0',B'1' 1 - Bracket state mgr reset to between-bracket state2
3 B'1' Conditional bracket termination
4 B'0' No alternate code
5

B'0' Sequence
  numbers not available
B'1' Sequence
  numbers available

 STSN request flag
6

B'0' BIS not sent
B'1' BIS sent

 BIS sent flag
7 B'0' Reserved
7 0-1 B'10' FM transaction mode, HDX-FF
2 B'1' Sender ERP
3 B'0' Secondary is first speaker
4-6 B'0000' Reserved
    If byte 6 bit 2 is 0, then
    0-Secondary speaks first after data traffic active state
7 B'0', B'1' 1-Primary speaks first after data traffic active state2
8 0-7 Unchanged Secondary send pacing count
9 0-7 Unchanged Secondary receive pacing count
10 0-7 Set from user Define receive-any SLU max send RU size3
11 0-7 Set from user Define outbuffer size PLU max send RU size
12 0-7 Unchanged Primary send pacing count
13 0-7 Unchanged Primary receive pacing count
      Presentation Services
14 0-7 X'06' LU profile (LUTYPE6)
15 0-7 X'00' Reserved Function management header subset
16 0 Reserved Primary half-session flags
1 Reserved  
2 1 - FMH6: Receive

SYSMSG supported

  
3 1 - Receive SCHEDULER

model supported

  
4 1 - Receive QMODEL supported  
5 0 - Linear file model ignored  
6 0 - DL/I model ignored  
7 Reserved  
17   Reserved  
18-19   Reserved  
20 0 Reserved Secondary half-session flags
1 Reserved  
2 1 - Receive SYSMSG supported  
3 0 - Receive SCHEDULER

not supported4

1 - Receive SCHEDULER

model supported

  
4 0 - Receive QMODEL

ignored

1 - Receive QMODEL

supported

  
5 0 - linear file model ignored  
6 0 - DL/I model ignored  
7 Reserved  
21   Reserved  
22-26   Reserved  
27 0-7   Length of PLU name
28-M     PLU name
M+1 0-7 X'00' No user data present Length of user data
M+2-N   X'00' Structured fields follow

X'00' First byte of unstructured user data5

 User data
M+3-N   Remainder of unstructured user data For unstructured user data
M+3-N   Structured fields For structured user data6
N+1 0-7 Structured fields, request correlation (URC) field

X'00' = no URC present

 Length of URC7
N+2-P   End-user-defined identifier URC4
P+1 0-7 X'00'=no secondary name Length of secondary LU name4
P+2-R 0-7 Secondary LU name Secondary LU name4
Notes:
  1. The length of the BIND RU cannot exceed 256 bytes; otherwise, a negative response is returned.
  2. Set to indicate possible in-bracket or process restart. Set by IMS on bind when response mode output remains on the queue or when IMS is in conversational mode. Can also be sent on a negotiated bind response by the other half session.
  3. The receive-any buffer size is determined by the user-supplied value for size on the RECANY keyword parameter of the COMM macro statement, less 28 bytes.
  4. When the bind indicates that the other half session does not support the SCHEDULER process, IMS sends all unsolicited and asynchronous output using ATTACH.
  5. Unstructured user data is ignored and not provided by IMS.
  6. Structured user data formats. A structured field contains architected or subsystem-defined information and provides a means for subsystems to communicate data. Each structured field contains a field identifier (subfield number) and length. A structured data field can contain unstructured data.

    If structured field (M+3-N) is X'00', it contains unstructured data as follows:

    1
    Length of unstructured data field (including subfield key field). If zero, this field can be omitted entirely.
    2
    Subfield key: X'00'
    3-N
    Unstructured data. If the structured subfield number is X'03', an 8-byte USERVAR name follows the subfield.

    If the structured field (M+3-N) is X'01', it contains a session qualifier as follows:

    1
    Length of session qualifier field (including subfield key field). If zero, this field can be omitted entirely.
    2
    Subfield key: X'01'
    3
    Length of primary resource qualifier (X'00' means no primary source qualifier is present). Values 0 to 8 are valid.
    4-N
    Primary resource qualifier
    N+1
    Length of secondary resource qualifier (X'00' means no secondary resource qualifier is present). Values 0 to 8 are valid.
    N+2-M
    Secondary resource qualifier
    M+1
    Length of password (X'00' means no password is present). Values 0 to 8 are valid.
    M+2-P
    Password. Ignored on bind or bind reply from IMS and is not sent on bind or bind reply. IMS indexes structured fields to find field X'01', a session-qualifier field, when these parameters are required for session initiation using parallel sessions.
    M+3-N
    If the structured field has a subfield of X'02', IMS interprets the field as an MSC partner ID. If bind is issued in an XRF environment that uses USERVAR instead of MNPS, an additional structured segment is included in the user data. The format of this segment is:
    1
    Length of USERVAR segment, X'09'
    2
    Subfield key, X'03'
    3-10
    8-byte field containing USERVAR of the XRF complex
  7. The URC and secondary LU name are not used by IMS but are shown for compatibility purposes.