CMSG—message switching
If you specify a delivery time on the current day that falls
within the past hour, it is interpreted as a request for
immediate delivery. An earlier time than that is
considered already passed and is treated as an error.
The following message is issued:
TIME ALREADY PASSED
Note that, if the current time is 00.15, T=2345 is
interpreted as 23.45 today because there has been a
change of date. The message is not therefore
transmitted immediately.
Logical unit destinations
This section describes the use of the CMSG transaction to
send messages to logical units. For details of message
handling within CICS subsystems, and of the use of the
message-switching transaction at subsystem terminals, see
the appropriate CICS/OS/VS subsystem guide.
Each logical unit in a CICS-SNA network is identified by a
single terminal identifier and, if the logical unit is capable of
receiving message text, messages may be routed to it in the
same way as they are routed to non-SNA terminals. Routing
by operator identifier may also be employed if the logical unit
supports operator signon, and SNA and non-SNA
destinations may be specified in the same ROUTE option.
The destination for a message sent to a logical unit can be a
display or printer device, or it can be a data set or an
application program in a subsystem controller. To the
message sender, the destination behaves like a “terminal”,
and any necessary formatting is performed by the CMSG
transaction or within the subsystem controller itself.
Logical device codes
Some types of logical unit (LU) can be used to get access to
more than one resource within a subsystem. For example,
data sent to a 3601 LU may be intended for an IBM 3604
Keyboard Display, an IBM 3618 Administrative Line Printer,
or some other element of the IBM 3600 Finance
Communication System. The facility provided by CICS to
permit destination selection within LUs of this type is the
logical device code (LDC).
The LUs that support destination selection by LDC are:
3601 LU
3770 batch LU
3770 batch data interchange LU
3790 batch data interchange LU.
For the user of the message-switching transaction, the LDC
is a 2-character mnemonic code whose meaning is defined
by the CICS installation. It may be used to qualify an LU
destination by including it in the ROUTE option in the syntax
diagram that follows:
55─ ──ROUTE= ────────────────────────────────────5
┌ ┐───────────────────────
5─ ──┬ ┬───
6┴─Termid──\ldc──/opid─ ──────── ─5%
├ ┤─ALL──\ldc───────────────────────
│ │┌┐───────────────────
└ ┘───
6┴─.termlist──\ldc─ ─┤ Idloop ├─
Idloop:
┌ ┐───────────────────────────
├─ ───
6┴┬┬─────────────────────── ─┤
└ ┘─,±termid──\ldc──/opid─
where:
*ldcis a 2-character LDC mnemonic preceded by an asterisk
(*) that qualifies the destinations. The *ldc parameter
may qualify an LU identifier (termid), a general broadcast
(ALL), or a terminal list table specification (.termlist).
The *ldc parameter applies only to LUs, not to any
start-stop or BSC terminals.
Different LDC mnemonics may be included in one
ROUTE option specification; however, all destinations for
one message must indicate the same device type.
Termid*ldc
associates an LDC mnemonic with an LU
identification.
ALL*ldc
is a general broadcast to all terminals with the same
LDC mnemonic qualifying all LUs.
Termlist*ldc
.termlist*ldc
qualifies all entries in this terminal list table with the
specified LDC mnemonic. This overrides any LDC
specified within the terminal list table. This LDC
specification does not apply to start-stop or BSC
terminals.
Note: This qualification of a TLT occurs before any
succeeding TLTs or +/− entries are
processed, see example 9 in “Examples of
3600 and 3770 batch destinations” on
page 240.
+termid*ldc/opid
adds a destination, if not a complete duplicate to
any contained in the requested TLTs.
−termid*ldc/opid
deletes duplicate destinations resulting from the
requested TLTs. A −termid*ldc, without an opid,
deletes all destinations of that termid*ldc (with or
without operator identifiers) resulting from the
requested TLTs. A −termid/opid, without an LDC
mnemonic, deletes all destinations of that
termid/opid (with or without LDC mnemonics)
resulting from the requested TLTs.
Chapter 19. Message switching CMSG 239