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The terminal services parameters that do not set bits in the communication control
byte are SEND, WAIT TERMINAL, and SAVE. Bits in the communication control
byte are set for the ISSUE DISCONNECT and CONVERSE parameters, and for the
FMH and LAST parameters on the EXEC CICS SEND command.
The CICS-TCAM interface does not support the RESET parameter or the 3270
parameters READB and COPY.
All messages to TCAM from CICS are prefixed with the standard CICS-TCAM
communication area. This is one byte for the non-SNA TCAM interface, and
two-bytes for the TCAM SNA interface (that is, when TCAMFET=SNA is specified in
DFHTCT TYPE=LINE). This area is used to convey to TCAM special requests and
options that cannot be used within CICS.
The format of the communication area is:
First byte
X'01' FMH present in stream
X'04' Extended CCB (2-byte CCB)
X'08' DISCONNECT request
X'10' READL (read keyboard)
X'20' WRITEL (write keyboard).
Second byte (present if extended CCB is on)
X'01' Last output from transaction (WRITE,LAST)
X'02' READ requested after this WRITE (WRITE,READ request or CONVERSE).
All other flags are reserved and are set to 0.
Generalized TCAM message format
Messages passed between CICS and TCAM and
vice versa
have the format shown
in Table 33.
Table 33. General format of TCAM messages
Destination CCB Device-
dependent data
FMH Message
8 bytes 2 bytes
(optional) (SNA
only)
x bytes (device-
dependent)
y bytes (SNA
only)
Destination
Destination name (8 bytes) taken from TCTTE’s netname parameter or from
DEST specification on output.
CCB Communication control bytes. This determines the options specified for the
message (for example, whether an FMH is present or not). The length of
the CCB varies, and can be:
0 bytes (input message, non-SNA)
1 byte (output message, non-SNA)
2 bytes (input/output messages, SNA).
TCAM devices
Chapter 26. Using TCAM with CICS 705