Use this system macro to generate the link keypoint (LK4KC) and channel
keypoints (LK5LC) that are required to operate and control TPF synchronous
links. These keypoints are stored on file as program records and
assembled by using one or more CTKL statements.
Format
If you want to generate a link keypoint,
use the following format. The parameters required in each case are
listed separately.
Each program record (segment) comprises one link keypoint and hence only
one CTKL macro is required within the envelope of BEGIN/FINIS
statements.
- TYPE=LK4
- Causes expansion of a link keypoint.
- P1024=YES|NO
- Defines whether the link operates according to the SITA link control
procedure P1024 or the ATA/IATA synchronous link control contained in ATA/IATA
interline communications manual DOC/GEN 1840, Chapter V.
- CHANS=literal1
- Defines the number of full duplex pairs (AI lines) comprising the
link. Its value can range from 1 to 7.
- RELSLN=literal2
- All lines attached to the TPF system are allocated sequential symbolic
line numbers defined in SYCON. Literal 2 defines the lowest numbered AI
line assigned to this link relative to the minimum symbolic line number
assigned to AI lines in SYCON. The lowest RELSLN value is 0
(zero).
- NEXT=symbol1
-
- LAST=YES
- These parameters are mutually exclusive and either provide, through
symbol1, the name of the next program record (segment) in the chain of
keypoints or else indicate, through LAST=YES, that this program record is the
last one in the chain.
- MAXBLK=literal3
- Defines the maximum number of characters in data message blocks exchanged
on the link from DLE to ETB inclusive. It does not include BCC.
The default value is 255.
- T1=literal4
- Defines the NAK/ENQ/Data Procedure timeout and repetition
frequency. The default value is 3 seconds.
- T2=literal5
- Defines the idle line timeout and repetition frequency. The default
value is 3 seconds.
- P=literal6
- Defines the frequency of acknowledging data message blocks
(notwithstanding the fact that all blocks of multiblock messages will be
acknowledged individually). The default value is 1.
- N2=literal7
- Defines the number of consecutive idle line or ENQ timeouts that cause the
line to be out of service (LOS). The default value is 3.
- HEN=literal8
- If the link is connected at its other end to a high level network (for
example SITA HLN) literal8 must be four hexadecimal characters defining the
address of entry centre (HEN) to that network. This parameter must be
included if P1024 = YES, otherwise a default value of zero is assumed.
- TSIEXH=literal9
- Defines the number of outstanding TSIs not acknowledged that causes the
TPF system to inhibit data message block transmission and enter the enquiry
procedure (TSI Exhaustion). The default value is 5.
- AML=YES|NO
- Defines whether AML link control blocks are exchanged when all blocks of a
multiblock message have been correctly received and acknowledged to clear that
message label for reuse by the transmitting center.
If the parameter is omitted, the value assigned depends on the parameter
P1024:
- P1024=YES generates AML=YES
- P1024=NO generates AML=NO.
If P1024=YES and AML=NO is coded, the parameter is accepted and a warning
message generated.
- SPREAD=YES|NO
- Defines whether blocks of multiblock messages can be transmitted on
different channels of a multichannel link (also called
scatter).
If the parameter is omitted, the value assigned depends on the parameter
P1024:
- P1024=YES generates SPREAD=NO
- P1024=NO generates SPREAD=YES.
If P1024=YES and SPREAD=YES is coded, the parameter is accepted and a
warning message generated.
- ILB=YES|NO
- Defines whether ILB link control blocks are exchanged in idle line
conditions. The default value is ILB=NO
If P1024=YES and ILB=YES is coded the parameter is accepted and a warning
message generated.
- ENQREP=ACK|RSM
- Defines whether the response to ENQ and ILB link control blocks are ACK in
addition to RSM or STP or are restricted to RSM or STP. The default
value is ENQREP = ACK.
- EXSYN=*|4|8|12
- Defines the number of extra SYN characters at the start of a data
transmission additional to the number generated automatically by the
hardware. The default value is 0 (zero).
- MBIXDLY=literal10
- Defines the time delay after discovering MBI exhaustion for A-type
messages before attempting further processing by the output message
handler. The default value is 6.
- MAXBQ=literal11
- Defines the maximum number of message blocks on the link B-type output
message queue which inhibits the output message handler from adding further
original message blocks. The default value is 3.
- RSTBQ=literal12
- Defines the minimum number of message blocks on the link B-type output
message queue which allows the CCP to control transfer to the output message
handler. The default value is 2.
- HDR=YES|NO
- Defines whether all A-type traffic on this link, with the exception of
traffic that originated from a pseudo high-speed line, contains routing
information in a standard message header, or not.
If this parameter is omitted, it is assumed that the message will not
contain routing information.
- ORIGID=literal13
- This parameter defines the symbolic origin application name assigned to
nonPLN, A-type traffic on a link that does not support the message routing
header. Literal 13 must be four decimal characters. A default of
0000 is generated if this parameter is required, but not included.
- DESTID=literal14
- This parameter defines the symbolic destination application name assigned
to nonPLN, A-type traffic on a link that does not support the TPF message
routing header. Literal 14 must be four decimal characters. A
default of 0000 is generated if this parameter is required, but not
included.
- ACI=OMIT|INCLUDE
- Defines whether the optional additional characteristics indicator (ACI)
byte is to be included in the control character envelope which accompanies
each information block. If the parameter is omitted, the value assigned
is dependent upon the P1024 specification:
- P1024=NO generates ACI=OMIT
- P1024=YES generates ACI=INCLUDE.
When actually coding the ACI parameter, the validity of the definition is
dependent upon the P1024 parameter. Therefore, P1024=NO, ACI=OMIT,
P1024=NO, ACI=INCLUDE, and P1024=YES, ACI=INCLUDE are valid combinations while
P1024=YES, ACI=OMIT are not valid combinations.
- LINCODE=CCITT#5|CCITT#2|EXITT#5|ALC
- Defines the code translation to be performed on message block text when
the optional ACI character is not a component of the control character
envelope (ACI=OMIT). If the parameter is omitted, the value generated
is LINCODE=CCITT#5. The text translation specifications follow
here.
- CCITT#5
- CCITT No. 5 code (ASCII/ISO 7 bit code)
- CCITT#2
- Padded CCITT No. 2 code (Padded Baudot)
- EXITT#5
- Extended CCITT No. 5 code
- ALC
- Padded 6 bit code (Padded ALC).
Only one translation code can be specified for each link when using this
parameter.
- T6=literal15
- Defines the time interval allowed between receipt of the last ACK of a
multiblock message and the acknowledge message label (AML) LCB before the
entire message will be retransmitted. T6 is an alternate value to T1
and overrides the latter when defined. The T6 parameter is invalid for
P1024 = YES.
When the alternate AML timer, T6, is defined, the value must be between 1
and 63 inclusive. When T6 is not to be defined, omit the
parameter.
- T7=literal16
- Defines the time interval allowed between receipt of successive blocks of
a multiblock message before the partially received message is
discarded. This parameter is invalid for P1024 = YES.
When a message discard timer value, T7, is used, the value must be between
1 and 63 inclusive. When T7 is not used, omit the parameter.
This implies that partially received messages will not undergo a "time out"
and be discarded.
- N3=literal17
- Defines the number of times a multiblock message is retransmitted in its
entirety when no Acknowledge Message Label (AML) LCB has been received.
This parameter is invalid for P1024 = YES.
When message retransmission is to occur, N3 must be a value specified
between 1 and 12 inclusive. When no message retransmission is to occur,
the N3 parameter must be omitted.
- S1=literal18
- No ACK received timer. After a message block has been sent, an ENQ
is generated by the link control handler if an ACK is not received within S1
seconds. The S1 timer is reset after an LCB with parity errors is
received and after a message block has been sent. Default value is
3.
- S7=literal19
- No block received timer. When no data or control block has been
received for more than S7 seconds, the link control handler generates an
ENQ. The S7 timer is reset upon receipt of a control or data block and
after an ENQ has been generated. Default value is 4.
- S8=literal20
- Channel down timer. When a channel is declared to be down, the link
control handler starts the channel down timer (S8). This timer is reset
should the link control handler declares the link down. While the S8
timer is running, the link control handler does not generate or accept data or
control blocks. When the timer expires an ENQ is generated.
Default value is 15.
- S10=literal21
- Multiblock message timer. If, during reception of a multiblock
message S10 seconds have elapsed during which another block of that message
has not been received, the link control handler gives to the supervisor those
blocks so far received and clears the message label. Default value is
60.
- Z5=literal22
- STP N/M repetitions. If, after a channel has been declared down,
other channels of the link remain operative, the link control handler sends Z5
SXTs at intervals of T1 seconds. Default value is 3.
- LOOPTST=YES|NO
- To describe whether or not a loop test configuration between two centers
will be established. Default is no.
- LOOPBIT=ONE|ZERO
- Subject to bilateral agreement between centers, bit 6 of the TSI in link
control blocks can be used to indicate the center originating the control
block. It is set to 1 at one end of the link and to 0 (zero) at the
other.
- RETRANS=YES|NO
- Indicator as to whether or not to retransmit complete message on channel
down condition. Default is no.
If you want to generate a channel
keypoint, use the following format.
Each program record (segment) makes up one channel keypoint. Hence,
only one CTKL macro is required between BEGIN and FINIS statement.
- TYPE=LK5
- Causes expansion of one channel keypoint
- CHANS=1
- Defines one channel keypoint to be generated by this CTKL
statement.
- RELSLN=literal14
- Literal14 defines the lowest numbered AI line whose keypoint is being
generated by this CTKL statement relative to the minimum symbolic line number
assigned to AI lines in SYCON. The lowest RELSLN value is 0
(zero).
- RELKCN=literal15
- Literal15 defines the lowest numbered AI line whose keypoint is being
generated by this CTKL statement relative to the first AI line comprising the
link. The lowest RELKCN value (for the first channel assigned to this
link) is 0 (zero).
- NEXT=symbol1
-
- LAST=YES
- See the previous section for information about the RELKCN parameter and
generating a LINK keypoint.
- Note:
- When more than one CTKL statement is necessary in one program assembly, each
requires this parameter.
- P=literal 6
- See the previous section for information about the P parameter and
generating a LINK keypoint.
- Note:
- When more than one CTKL statement is necessary in one program assembly, each
requires this parameter.
- TSIEXH=literal9
- See the previous section for information about the TSIEXH parameter and
generating a LINK keypoint.
- Note:
- Where more than one CTKL statement is necessary in one program assembly, each
requires this parameter.
Entry Requirements
SYGLB, SYSET, SYCON, and CAIEQ must be called before issuing the CTKL
macro.
Return Conditions
This is not an executable macro, therefore return conditions are not
applicable.
Programming Considerations
- Only one link keypoint or up to three channel keypoints can be
accommodated in one program segment.
- Prior to loading the program segments containing the CTKL statements it is
necessary to allocate file storage space for them. This is performed by
assigning four character segment names and inserting them into the system
allocator.
- If these constitute the first special program records in the system, the
programmer must ensure that the name of the first segment in the chain is
correctly assembled into the CIJH program. If these records extend to
an existing chain, the forward chain field of the previous last-in-chain must
be updated to reflect the new next-in-chain.
- The macro defining the Global 3 Directory (GL0BY) must be updated to
reflect these special program records.
- I-stream restrictions are not applicable to this macro.
Examples
None.