The mapping control program (DFHMCP) is the interface between application
programs and the modules that perform mapping, message switching,
page and text building, device-dependent output preparation, and message
disposition to terminals, temporary-storage areas, or the application
program.
Figure 1 shows the relationships
between the components of mapping control. Figure 1. Mapping control
program interfaces
Note:
This program is entered
when an application program issues a request for basic mapping support
services.
It may also be called by task control to process a deferred work
element (DWE) if an application program terminates and there are partial
pages in storage, or the message control record (MCR) created during
execution of the task has not been placed in temporary storage.
The following information is returned to the requester: error
codes, page overflow information, and (for a SEND MAP SET or SEND
TEXT SET command) a list of completed pages.
DFHMCP communicates with temporary storage control to put the
MCR for routed or stored messages, if a ROUTE command, or SEND MAP
PAGING or SEND TEXT PAGING command is issued. A DELETEQ TS command
is issued to request that a message be purged from temporary storage
if a PURGE MESSAGE command is issued.
DFHMCP communicates with storage control to:
Acquire and free storage in which the MCR is built (a SEND MAP
command after a SEND MAP PAGING, SEND TEXT PAGING, or ROUTE command)
Acquire and free storage in which to copy the message title (a
ROUTE command with the TITLE option specified)
Acquire storage to build automatic initiate descriptors (AIDs)
for non-routed messages, or routed messages to be delivered immediately
(a SEND PAGE command)
Acquire a BMS work area (OSPWA) at the time of the initial BMS
request
Acquire and free an area used for user request data if a SEND
PAGE command must be simulated before processing the user’s
request
Free the returned page list (a DELETEQ TS command)
Free map copies if SEND PAGE command was issued and pages were
being built in response to SEND PAGE commands
Free terminal type parameters (TTPs) (SEND PAGE command).
DFHMCP communicates with program manager to:
Load and delete map sets
Link to the terminal page retrieval program (DFHTPR) to process
one or more pages of a message if a SEND PAGE command is issued with
the RETAIN or RELEASE option specified
Abnormally terminate tasks that incur errors that cannot be corrected.
DFHMCP communicates with interval control to:
Initiate transaction CSPQ
Obtain the current time of day, which is then used to time stamp
AIDs for routed messages
Initiate transaction CSPS for messages to be delivered later.
DFHMCP communicates with task control to schedule transaction
CSPQ for every terminal that is to receive a routed message to be
delivered immediately.
Transient data control is used to send error and information messages
to the main terminal.
Route list resolution (DFHRLR) is used to collect terminals from
a user-supplied route list or from the entire TCT by terminal type,
and build a terminal type parameter (TTP), which controls message
building, for each terminal type. It is also used to build a single-element
TTP for the originating terminal.
Non-3270 input mapping (DFHIIP) is used to process RECEIVE MAP requests for a terminal other than an IBM® 3270 Information Display System.
The mapping control program calls DFHMCX if the request is eligible
for the BMS fast-path module.
3270 mapping (DFHM32) is used to process RECEIVE MAP requests for an IBM 3270 Information Display System.
Page and text build (DFHPBP) processes the following output requests:
Page and text build program (DFHPBP) processes all BMS output
requests
SEND MAP
SEND MAP PAGING
SEND MAP SET
SEND PAGE
SEND TEXT
SEND TEXT PAGING
SEND TEXT SET.
For 3270 output, DFHM32 is called; for other output, DFHML1
is called.
The partition handling program (DFHPHP) is called when the data
is in an inbound structured field. DFHPHP extracts the partition
ID, device AID, and cursor address.
