BIND image and response

Table 2 and Table 3 indicate the BIND fields that an application program can set and those that VTAM sets. The values for fields that the application program can set are obtained as shown in Table 1.

Table 1. LOGON and SCIP exits and the BIND
Application Program	BIND Field Value Obtained
Has no LOGON exit or does not supply a BIND image request (session parameters)	From the corresponding field in the pending CINIT request or is set by VTAM
Has no SCIP exit or does not supply a BIND image response (session parameters)	From the corresponding field in the received BIND or is set by VTAM

The options available to an application program are listed in Table 2 and Table 3. These options apply only when VTAM sends the BIND or BIND image.

Note: The application program might provide session parameters. These parameters, if provided, do not include the BIND request code byte. If the BIND image that is received is to be mapped with the ISTDBIND DSECT, base the DSECT on byte 1 of the BIND image, not byte 0, which contains the X'31' request code.

For example, if you specify the BIND image using the RPLAREA of the APPCCMD CONTROL=OPRCNTL, QUALIFY=ACTSESS macroinstruction, the address specified in the RPLAREA should be the beginning of the ISTDBIND. It begins with the BIND format and type that follows the X'31' request code. Refer to z/OS Communications Server: SNA Programmer's LU 6.2 Reference for the ISTDBIND DSECT.

Although architecturally the PLU name in the BIND is a variable-length field, the ISTDBIND DSECT treats it as an 8-byte name. If the actual name is fewer than 8 bytes, pad it with blanks when using ISTDBIND to build the session parameters. The BIND area must match the ISTDBIND DSECT, not the BIND RU.

Byte 13 of the ISTDBIND (byte 14 of the BIND RU) is the first byte of the presentation services usage field, which continues through byte 24 of the ISTDBIND (byte 25 of the BIND RU). This field is used to specify optional protocols or data streams that apply to the specific type of LU. However, an LU 6.2 application program has control of only byte 23 of the BIND RU.

Some fields that VTAM sets in the BIND are determined by vectors that are passed to VTAM when the application opens an ACB. These vectors are located in the application-ACB vector list and mapped by the ISTVACBV DSECT. See Vector lists used during OPEN processing for more information.

For information on setting the session parameter fields, refer to z/OS Communications Server: SNA Programming.

Table 2. Bind request unit fields the application program can set
BIND RU	ISTDBIND	Use	Application's Options	VTAM's Action
Byte 0	(Not present)	Request code	Not accessible to the application program	VTAM sets to X'31'.
Byte 1	Byte 0 BINFMTY	Format and type Bit Meaning 0–3 Format 4–7 Type	VTAM ignores or overrides application program's setting.	VTAM sets to X'00'.
Byte 2	Byte 1 BINFM	FM profile	VTAM ignores or overrides application program's setting.	VTAM sets to X'13'.
Byte 3	Byte 2 BINTS	TS profile	VTAM ignores or overrides application program's setting.	VTAM sets to X'07'.
Byte 4	Byte 3 BINPRIP	FM usage, PLU Bit Meaning 0 Chaining 1 Request control 2–3 Chain response 4–6 Reserved 7 Send end bracket indicator	VTAM ignores or overrides application program's setting.	VTAM sets to X'B0'.
Byte 5	Byte 4 BINSECP	FM usage, SLU Bit Meaning 0 Chaining 1 Request control 2–3 Chain response 4–6 Reserved 7 Send end bracket indicator	VTAM ignores or overrides application program's setting.	VTAM sets to X'B0'.
Byte 6	Byte 5 BINCMNP	FM usage, common Bit Meaning 0 Segmenting 1 FM Header use 2 Bracket usage 3 Bracket term rule 4 Alternate code 5–6 Reserved 7 BIND RSP queue capability	VTAM ignores or overrides application program's setting.	VTAM sets to X'50'.
Byte 7	Byte 6 BINCMNP2	FM usage, common
		Bit Meaning 0–1 Send/Receive Mode	VTAM ignores or overrides application program's setting.	VTAM sets to half-duplex flip-flop (B'10') if the application specified PARMS=(FDX=NO), or defaulted this field on the ACB. VTAM sets to B'00' Full-Duplex if the application specified PARMS=(FDX=YES) on the ACB.
		2 Symmetric responsibility for recovery	VTAM ignores or overrides application program's setting.	VTAM always sets this value to B'1', symmetric responsibility for recovery.
		3 Primary/secondary Primary 1=Primary is brackets first speaker and contention winner; secondary is brackets bidder and contention loser. Secondary 0=Secondary is brackets first speaker and contention winner; primary is brackets bidder and contention loser.	VTAM ignores or overrides application program's setting.	VTAM sets to B'1' or B'0' depending on session polarity.
		4–5 Alternate code processing identifier	VTAM ignores or overrides application program's setting.	VTAM APPC code sets to B'00'.
		6 Control vectors are included after the SLU name	VTAM ignores or overrides application program's setting.	VTAM's APPC code sets to B'0'. Subsequent processing may set to B'1'.
		7 Reset state for Half-Duplex flip-flop (for example, at start of session.) 1=Primary sends first.	VTAM ignores or overrides application program's setting.	VTAM sets to B'1'.
Byte 8	Byte 7 BINAPACE	SLU's send pacing window Bit Meaning 0 Staging indicator 1 Reserved 2–7 Secondary TC's send window size	VTAM ignores or overrides application programs' setting.	VTAM sets bits 0–1. Bits 2–7 are copied and used for tuning in adaptive session pacing. Adaptive session pacing is always used unless the pacing stage endpoints are not at the appropriate level.
Byte 9	Byte 8 BINRPACE	SLU's receive pacing window Bit Meaning 0 Adaptive pacing 1 Reserved 2–7 Secondary TC's receive window size	VTAM ignores or overrides application programs' setting.	VTAM sets bit 0 to B'1'. Bits 2–7 are copied and used for tuning in adaptive session pacing.
Byte 10	Byte 9 BINRUSZ	SLU's maximum RU size	Application program can set from X'80'–X'FF'.	If the application program sets maximum RU size to 0 (unspecified) or less than 256, VTAM overrides this value with a value of 4096 (X'89'). Note: RU sizes corresponding to values X'01' through X'7F' are not supported architecturally. The high order bit of the maximum RU size must be set to 1 for the byte to be interpreted as a supported value.
Byte 11	Byte 10 BINPRUSZ	PLU's maximum RU size	Application program can set from X'80'–X'FF'.	If the application program sets maximum RU size to 0 (unspecified) or less than 256, VTAM overrides this value with a value of 4096 (X'89'). Note: RU sizes corresponding to values X'01' through X'7F' are not supported architecturally. The high order bit of the maximum RU size must be set to 1 for the byte to be interpreted as a supported value.
Byte 12	Byte 11 BINSPACE	PLU's send pacing window Bit Meaning 0 Staging indicator 1 Reserved 2–7 Primary TC's send window size	VTAM ignores or overrides application programs' setting.	VTAM sets bits 0–1. Bits 2–7 are copied and used for tuning in adaptive session pacing.
Byte 13	Byte 12 BINBPACE	PLU's receive pacing window Bit Meaning 0–1 Reserved 2–7 Primary TC's receive window size	Application program can set bits 2-7 to X'00' - X'3F'. VTAM overrides if value greater than CINIT bind image.	If bits 2-7 are 0, VTAM defaults to a receive pacing window of 32767 (X'7FFF').
Byte 14	Byte 13 BINLUP	PS profile Bit Meaning 0 PS usage format 1–7 LU type 6	VTAM ignores or overrides application program's setting.	VTAM sets to X'06'.
Byte 15	Byte 14 BINPSCHR	PS usage Bit Meaning 0 LU-6 level 1–7 Level 2	VTAM ignores or overrides application program's setting.	VTAM sets to X'02'.
Bytes 16–21	Bytes 15–20	Reserved or retired	VTAM ignores or overrides application program's setting.	VTAM sets to X'00000000000000'.
Byte 22	Byte 21 BINDSSSP BINDESS	Distributed Systems SecurityExtended Security Sense Codes Bit Meaning 0 Support for third party DCE security services 1 Extended Security Sense Codes 2–7 Reserved	VTAM ignores or overrides application program's setting.	If the application supplies a local-application's-DCE-capability vector (ISTVAC82) and indicates support for DCE security, then VTAM sets bit 0 to B'1'. If the application supplies an application-capabilities vector (ISTVAC81) and indicates support for extended security sense codes (VAC81ESS), then VTAM sets bit 1 to B'1'.
Byte 23	Byte 22	Bit Meaning 0–2 Reserved 3 FMH-5 security subfields support indicator 4 Session-level verification protocol support indicator 5 Password substitution indicator 6 Already-verified support indicator 7 Persistent-verification support indicator (MVS™ only)	Application program can set bits 3, 6, and 7 but only on the initial session with a partner LU. After a session is established with a partner LU, these bits are ignored if the application program sets them. Bits 6 and 7 can be set only if bit 3 is also set. If the application sets bit 5, VTAM ignores or overrides this setting.	If the application program does not provide a BIND image, VTAM sets bits 3, 6, and 7 according to the value specified on the SECACPT operand of the APPL definition statement. If a security management product also provides conversation security information, the most secure level of security will be used. Other bits in the byte are set to B'0'. For the initial session with the partner, VTAM sets bit 5 if the application indicates support for password substitution in its application-capabilities vector. For subsequent sessions with this partner, VTAM sets bit 5 according to the negotiated support for password substitution.
Byte 24	Byte 23	Bit Meaning 0 Reserved	VTAM ignores or overrides application program's setting.	VTAM sets to B'0'.
		1–2 Sync point, backout support	VTAM ignores or overrides application program's setting.	If this is the first session to the partner, VTAM sets this field as specified by the SYNCLVL operand on the APPL definition statement. That is, VTAM sets the field to B'10' if SYNCLVL=SYNCPT and sets the field to B'01' if SYNCLVL=CONFIRM. If this is not the first session to the partner, VTAM sets this field as the prior sessions have set this field.
		3 Reconnect support	VTAM ignores or overrides application program's setting.	VTAM sets to B'0'.
		4–5 Session reinitiation	VTAM ignores or overrides application program's setting.	VTAM sets to B'00' for parallel-session partners or B'11' for single-session partners.
		6 Parallel- session support	VTAM ignores or overrides application program's setting.	VTAM sets the bit to B'0' (not supported) if the BIND image contained in the CINIT-specified single session.
		7 CNOS support	VTAM ignores or overrides application program's setting.	VTAM's APPC support ensures the CNOS support bit has the same value as the parallel-session support bit.
Byte 25	Byte 24	Bit Meaning 0 Reserved 1 Limited-resource support 2–5 Reserved 6–7 Data compression indicators	VTAM ignores or overrides application program's setting.	VTAM's APPC support sets these fields to zero. Other components of VTAM may override this setting. For example, limited resources support is set to 1 if LIMRES is specified on the LINE or PU definition statement.
Byte 26	Byte 25 BINCRCTL	Cryptography support	VTAM ignores or overrides application program's setting.	VTAM sets this based on the ENCR setting on the APPL statement.
Byte 27	Byte 26 BINPRIML	PLU name length	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes 28–m	Bytes 27–m BINPRIMN	PLU name	VTAM ignores or overrides application program's setting.	VTAM sets.
Byte m+1	Byte m+1 BINUSEL	User data length	Application can set.	VTAM can set.
Byte m+2	Byte m+2	User data key	Application program can set. If the application program plans to supply unformatted user data, the user data key must be set to X'00'.	VTAM can set.
Bytes m+3–o	Bytes m+3–o	Unformatted user data	Application program can set.	VTAM copies from BIND supplied by application program.
Bytes o+1–p	Bytes o+1–p	Mode name subfield	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes p+1–q	Bytes p+1–q	Session instance ID subfield	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes q+1–r	Bytes q+1–r	Network-qualified PLU network name	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes r+1–t	Bytes r+1–t	Random data	VTAM ignores or overrides application program's setting.	VTAM sets if session level verification is used.
Bytes t+1–u	Bytes t+1–u	URC	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes u+1–v	Bytes u+1–v	SLU name	VTAM ignores or overrides application program's setting.	VTAM sets.

Table 3. Bind response unit fields the application program can set
BIND RU	ISTDBIND	Use	Application's Options	VTAM's Action
Byte 0	(Not present)	Request code	Not accessible to the application program	VTAM sets to X'31'.
Byte 1	Byte 0 BINFMTY	Format and type Bit Meaning 0–3 Format 4–7 Type	VTAM ignores or overrides application program's setting.	VTAM sets to X'00'.
Byte 2	Byte 1 BINFM	FM profile	VTAM ignores or overrides application program's setting.	VTAM sets to X'13'.
Byte 3	Byte 2 BINTS	TS profile	VTAM ignores or overrides application program's setting.	VTAM sets to X'07'.
Byte 4	Byte 3 BINPRIP	FM usage, PLU Bit Meaning 0 Chaining 1 Request control 2–3 Chain response 4–6 Reserved 7 Send end bracket indicator	VTAM ignores or overrides application program's setting.	VTAM sets to X'B0'.
Byte 5	Byte 4 BINSECP	FM usage, SLU Bit Meaning 0 Chaining 1 Request control 2–3 Chain response 4–6 Reserved 7 Send end bracket indicator	VTAM ignores or overrides application program's setting.	VTAM sets to X'B0'.
Byte 6	Byte 5 BINCMNP	FM usage, common Bit Meaning 0 Segmenting 1 FM header use 2 Bracket usage 3 Bracket term rule 4 Alternate code 5–6 Reserved 7 BIND RSP queue capability	VTAM ignores or overrides application program's setting.	VTAM sets to X'50'.
Byte 7	Byte 6 BINCMNP2	FM usage, common
		Bit Meaning 0–1 Send/Receive Mode	VTAM ignores or overrides application program's setting.	VTAM sets to B'00' (full-duplex) if both of the following items are true: The BIND request contained B'00' The application specified PARMS=(FDX=YES) on the ACB. Otherwise, VTAM sets B'10' (half-duplex) and the session is limited to half-duplex capability.
		2 Symmetric responsibility for recovery	VTAM ignores or overrides application program's setting.	VTAM always sets this value to B'1', symmetric responsibility for recovery.
		3 Primary/secondary Primary 1=Primary is brackets first speaker and contention winner; secondary is brackets bidder and contention loser. Secondary 0=Secondary is brackets first speaker and contention winner; primary is brackets bidder and contention loser.	VTAM ignores or overrides application program's setting.	VTAM sets to B'1' or B'0' depending on session polarity.
		4–5 Alternate code processing identifier	VTAM ignores or overrides application program's setting.	VTAM APPC code sets to B'00'.
		6 Control vectors are included after the SLU name	VTAM ignores or overrides application program's setting.	VTAM APPC code sets to B'0', subsequent processing may set to B'1'.
		7 Reset state for Half-Duplex flip-flop (for example, at start of session.) 1=Primary sends first.	VTAM ignores or overrides application program's setting.	VTAM sets to B'1'.
Byte 8	Byte 7 BINAPACE	SLU's send pacing window Bit Meaning 0 Staging indicator 1 Reserved 2–7 Secondary TC's send window size	Application program can set bit bits 2–7 to X'00'–X'3F'.	VTAM sets bits 0–1. If the pacing stage endpoint supports PU type 2.1 protocols, VTAM sets bits 2–7 to X'00'. Otherwise, VTAM copies bits 2–7 from the BIND response supplied by the application program.
Byte 9	Byte 8 BINRPACE	SLU's receive pacing window Bit Meaning 0 Adaptive pacing 1 Reserved 2–7 Secondary TC's receive window size	Application program can set bits 2–7 to X'00'–X'3F'.	If the pacing stage endpoint supports PU type 2.1 protocols, VTAM sets bit 0 to B'1' and bits 2–7 to X'00'. Otherwise, VTAM copies bits 2–7 from the BIND response supplied by the application program.
Byte 10	Byte 9 BINRUSZ	SLU's maximum RU size	Application program cannot change this to less than 256.	VTAM rejects the session if this value is less than 256. Note: RU sizes corresponding to values X'01' through X'7F' are not supported architecturally. The high order bit of the maximum RU size must be set to 1 for the byte to be interpreted as a supported value.
Byte 11	Byte 10 BINPRUSZ	PLU's maximum RU size	Application program cannot change this to less than 256.	VTAM rejects the session if this value is less than 256. Note: RU sizes corresponding to values X'01' through X'7F' are not supported architecturally. The high order bit of the maximum RU size must be set to 1 for the byte to be interpreted as a supported value.
Byte 12	Byte 11 BINSPACE	PLU's send pacing window Bit Meaning 0 Staging indicator 1 Reserved 2–7 Primary TC's send window size	Application program can set bits 2–7 to X'00'–X'3F'.	VTAM sets bits 0–1. If the pacing stage endpoint supports PU type 2.1 protocols, VTAM sets bits 2–7 to X'00'. Otherwise, VTAM copies bits 2–7 from the BIND response supplied by the application program.
Byte 13	Byte 12 BINBPACE	PLU's receive pacing window Bit Meaning 0–1 Reserved 2–7 Primary TC's receive window size	Application program can set bits 2–7 to X'00'–X'3F'.	VTAM sets bits 0–1. If the pacing stage endpoint supports PU type 2.1 protocols, VTAM sets bits 2–7 to X'00'. Otherwise, VTAM copies bits 2–7 from the BIND response supplied by the application program.
Byte 14	Byte 13 BINLUP	PS profile Bit Meaning 0 PS usage format 1–7 LU type 6	VTAM ignores or overrides application program's setting.	VTAM sets to X'06'.
Byte 15	Byte 14 BINPSCHR	PS usage Bit Meaning 0 LU-6 level 1–7 Level 2	VTAM ignores or overrides application program's setting.	VTAM sets to X'02'.
Bytes 16–21	Bytes 15–20	Reserved or retired	VTAM ignores or overrides application program's setting.	VTAM sets to X'00000000000000'.
Byte 22	Byte 21 BINDSSSP BINDESS	Distributed Systems SecurityExtended Security Sense Codes Bit Meaning 0 Support for third party DCE security services 1 Extended Security Sense Codes 2–7 Reserved	VTAM ignores or overrides application program's setting.	If the application supplies a local-application's-DCE-capability vector (ISTVAC82) and indicates support for DCE security, then VTAM sets bit 0 to B'1'. If the application supplies an application-capabilities vector (ISTVAC81) and indicates support for extended security sense codes (VAC81ESS), then VTAM sets bit 1 to B'1'.
Byte 23	Byte 22	Bit Meaning 0–2 Reserved 3 FMH-5 security subfields support indicator 4 Session-level verification protocol support indicator 5 Password substitution indicator 6 Already-verified support indicator 7 Persistent-verification support indicator (MVS only)	Application program can set bits 3, 6, and 7 but only on the initial session with a partner LU. After a session is established with a partner LU, these bits are ignored if the application program sets them. Bits 6 and 7 can be set only if bit 3 is also set. If the application sets bit 5, VTAM ignores or overrides this setting.	If the application program does not provide a BIND image, VTAM sets bits 3, 6, and 7 according to the value specified on the SECACPT operand of the APPL definition statement. If a security management product also provides conversation security information, the most secure level of security will be used. For the initial session with the partner, VTAM sets bit 5 if both the partner LU and the local application indicate support for password substitution. For subsequent sessions with this partner, VTAM sets bit 5 according to the negotiated support for password substitution. Other bits in the byte are set to B'0'.
Byte 24	Byte 23	Bit Meaning 0 Reserved	VTAM ignores or overrides application program's setting.	VTAM sets to B'0'.
		1–2 Sync point, backout support	VTAM ignores or overrides application program's setting.	If this is the first session to the partner, VTAM negotiates this value as follows: If the value received on the BIND is B'01' (CONFIRM), then VTAM echoes this value in the response. If the value received on the BIND is B'10' (SYNCPT) and SYNCLVL=SYNCPT on the APPL statement, then VTAM echoes B'10' on the response. If the value received on the BIND is B'10' (SYNCPT) and SYNCLVL=CONFIRM on the APPL statement, then VTAM negotiates the response to B'01' (CONFIRM). If this is not the first session to the partner, VTAM sets this field as the prior sessions have set the field.
		3 Reconnect support	VTAM ignores or overrides application program's setting.	VTAM sets to B'0'.
		4–5 Session reinitiation	VTAM ignores or overrides application program's setting.	VTAM sets to B'00' for parallel-session partners. For single-session partners, VTAM copies the value from the BIND request.
		6 Parallel- session support	Application program can set.	VTAM overrides the application program's setting and sets the bit to B'0' (not supported) if the BIND image specified single session.
		7 CNOS support	Application program can set.	VTAM ensures that the CNOS support bit has the same value as the parallel-session support bit.
Byte 25	Byte 24	Bit Meaning 0 Reserved 1 Limited-resource support 2–5 Reserved 6–7 Data compression indicators	VTAM ignores or overrides application program's setting.	VTAM's APPC support echoes these fields. Other components of VTAM may modify these bits as appropriate. For example, Limited Resource will be set to 1 if LIMRES is specified on the LINE or PU macroinstruction.
Byte 26	Byte 25 BINCRCTL	Cryptography support	VTAM ignores or overrides application program's setting.	VTAM sets based on the setting of the ENCR keyword as specified, for example, on the APPL statement and other appropriate macroinstructions.
Byte 27	Byte 26 BINPRIML	PLU name length	VTAM ignores or overrides application program's setting.	Reserved on response. VTAM sets to X'00'.
Bytes 28–m	Bytes 27–m BINPRIMN	PLU name	VTAM ignores or overrides application program's setting.	Reserved on response. VTAM copies from BIND request.
Byte m+1	Byte m+1 BINUSEL	User data length	Application program can set.	VTAM can set.
Byte m+2	Byte m+2	User data key	Application can set. If the application program wishes to supply unformatted user data, the user data key must be set to X'00'.	VTAM can set.
Bytes m+3–o	Bytes m+3–o	Unformatted user data	Application program can set.	VTAM copies from BIND supplied by application program.
Bytes o+1–p	Bytes o+1–p	Mode name subfield	VTAM ignores or overrides application program's setting.	VTAM copies from BIND request.
Bytes p+1–q	Bytes p+1–q	Session instance ID subfield	VTAM ignores or overrides application program's setting.	VTAM copies from BIND request.
Bytes s+1–t	Bytes s+1–t	Network-qualified SLU network name	VTAM ignores or overrides application program's setting.	VTAM sets.
Bytes q+1–r	Bytes q+1–r	Random data X'11'	VTAM ignores or overrides application program's setting.	VTAM sets as appropriate.
Bytes r+1–s	Bytes r+1–s	Enciphered random data X'12'	VTAM ignores or overrides application program's setting. End of userdata subfields.	VTAM sets as appropriate.
Bytes t+1–u	Bytes t+1–u	URC	VTAM ignores or overrides application program's setting.	VTAM does not set.
Bytes u+1–v
Bytes u+1–v	SLU name	VTAM ignores or overrides application program's setting.	VTAM does not set. Reserved upon response.