This section describes the runtime parameters used for Adabas Transaction Manager.
ATM execution is controlled mainly through ADARUN (ADARUN DDCARD input)
runtime parameters. When executing the ATM transaction manager, the parameter
setting ADARUN DTP=TM must be provided. All other ATM
runtime parameters, all of which begin with “TM”, will be effective only when
ADARUN DTP=TM is specified. They are ignored for all
other values of DTP. For more information on the DTP parameter, see the
Adabas Operations documentation.
Note:
Adabas databases that participate in two-phase commit processing must
execute as resource managers with ADARUN DTP=RM.
Note:ADARUN NONDES=YES (non-descriptor search
allowed) is required for the ATM transaction manager.
The following section describes each ATM runtime parameter:
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime |
Sets the number of entries allowed in the transaction manager’s internal request queue. |
10 - 32767 | 10 |
The ATM transaction manager uses an internal request queue for scheduling some of the tasks it needs to perform. The TMDRQ parameter determines the total number of entries in the queue that is used to service certain incoming, asynchronous requests. This queue is currently used only when the ATM RRMS interface is active.
When the RRMS interface is in use, the ATM dynamic request queue (DRQ) is used for communication between ATM RRMS exits and the ATM manager. The value specified for the TMDRQ parameter should therefore be increased if RRMS is to be used. Consider the number of global transactions that may reach a syncpoint at the same time, and increase TMDRQ by this number. You can specify a higher value, for safety, without incurring any performance degradation.
You can use Online Services to monitor usage of the DRQ. If you specify too small a value and the DRQ becomes full, backouts resulting in response code 9 are likely to occur.
ATM will allow 250 entries in its internal request queue.
ADARUN PROG=ADANUC,DTP=TM,TMDRQ=250
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime |
Location of |
ATM | TARGETS | TARGETS |
The TMETDATA parameter determines
the database or databases that will store ET data.
The same TMETDATA parameter value must
be specified for all Adabas Transaction Manager (ATM) instances on the
network.
Possible values:
| Value | Explanation |
|---|---|
| ATM |
|
| TARGETS |
If the client storing
|
Notes:
ET data is to be stored in the transaction
manager's database only.
ADARUN PROG=ADANUC,DTP=TM,TMETDATA=ATM
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime |
Sets time limit during which a global transaction can be open without being prepared. |
1 - 16777215 | 720 |
The TMGTT parameter approximately specifies the maximum elapsed time, in units of 1.048576 seconds, that a global transaction can remain open without being prepared. If the limit is exceeded, ATM automatically backs out the global transaction from all affected databases. The next time the client issues a transactional Adabas command, a response code 9 is returned.
It is recommended that TMGTT be smaller than the lowest TT parameter of any database running with DTP=RM.
The TMGTT parameter does not supersede the TT parameter settings of other databases. If a database times out a client who has an unprepared global transaction open, the global transaction is subsequently backed out. A response code 9 is returned if the client then issues a transactional command.
Note:
Transaction timout can happen when a client session stops issuing
commands for a period of time. In these circumstances the transaction manager
has no opportunity to give a response code to the client, to indicate that the
timeout has taken place. In such cases, the pending response code will be
preserved and returned to the client at the first possible opportunity. For
further details, please refer to Pending Response Codes in
the Adabas Transaction Manager introduction.
ATM will back out global transactions that are not prepared within about 600 seconds (10 minutes) of the first transactional command.
ADARUN PROG=ADANUC,DTP=TM,TMGTT=600
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime | Controls the logging option for the current execution of the ATM manager. | YES | NO | NEVER | NO |
The ATM manager can log internal events for diagnostic purposes using a dual logging system. It can
maintain a log buffer area in memory that contains details of the latest logged events;
maintain transaction-related event details in storage areas related to specific global transactions;
write every log record to dual sequential ATMLOG datasets.
Possible values:
| Value | Description |
|---|---|
| YES | The ATM manager writes every record to an ATMLOG
dataset. The ATM manager keeps a record of the latest internal events in its
global log buffer area. It also maintains the contents of log buffer areas
related to open global transactions. Logging to the ATMLOG datasets can be
deactivated at any time using the operator command TM
NOLOG.
|
| NO | The ATM manager will not write log records to the
ATMLOG datasets. Logging to the ATMLOG datasets can be activated at any time
using the operator command TM LOG. The ATM manager
keeps a record of the latest internal events in its global log buffer area; it
also maintains the contents of log buffer areas related to open global
transactions.
|
| NEVER | ATM logging is disabled for the duration of this execution of the ATM manager. |
On z/OS and VSE systems, if the ATM manager writes log records to the
ATMLOG (TMLOG=YES or TM
LOG issued) and the dataset currently in use becomes full, the
manager closes that dataset and switches to the other dataset. Automatic log
switching currently does not take place on BS2000 systems. A system message
might appear in the console log, indicating that the first log dataset has
become full. You may also switch between the two ATMLOG datasets by using the
operator command TM FEOFLOG. Whenever the ATMLOG
datasets are switched, a message is displayed on the console indicating the
dataset that is currently in use.
The ATM manager is to maintain its internal log buffer areas and write all log records to the ATMLOG datasets.
ADARUN PROG=ADANUC,DTP=TM,TMLOG=YES
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime | Sets severity threshold for the suppression of warning messages. | 0 | 4 | 8 | 0 |
Every message that the ATM manager sends to the console and to the DDPRINT dataset has a severity level. Message severity levels are explained in the Adabas Transaction Manager Messages and Codes.
Using the TMMSGSEV parameter, you can prevent messages with low severity levels from being written to the console by the ATM manager. This parameter has no effect on messages that are issued by the ATM client proxy, or during the early part of the transaction manager’s initialization.
All messages created by the ATM manager are written to DDPRINT regardless of the TMMSGSEV specification.
Possible values:
| Value | Description |
|---|---|
| 0 | No messages are suppressed. |
| 4 | Messages of severity less than 4 are not sent to the console. |
| 8 | Messages of severity less than 8 are not sent to the console. |
The ATM manager should not send message of severity less than 4 to the console.
ADARUN PROG=ADANUC,DTP=TM,TMMSGEV=4
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime | Controls restart handling of problematic transactions. | NORMAL | FORCE | FORCEALL | NORMAL |
When an ATM manager restarts, it rebuilds its global transaction list as nearly as possible to its latest state when it was last executing. It then attempts to complete or back out any incomplete global transactions. The TMRESTART parameter determines the manager’s restart action with regard to global transactions and transaction branches that remain incomplete at the end of this process.
Possible values:
| Value | Description |
|---|---|
| NORMAL | Any incomplete transactions remain in an incomplete state until such time as they can be completed. |
| FORCE | ATM transfers to the suspect transaction journal (STJ) the details of every incomplete global transaction that has its root local to this ATM manager. The details of these transactions are deleted from ATM’s recovery information, the originating clients are closed, and any related internal resources are freed. ATM can no longer guarantee integrity for such global transactions. |
| FORCEALL | Details of all unresolved global transactions and transaction branches are transferred to the STJ. The details are deleted from ATM’s recovery information, the originating clients are closed, and any related internal resources are freed. ATM can no longer guarantee integrity for the affected global transactions. |
After recording them in the STJ, the ATM manager is to discard details of any global transactions that it owns, and that remain incomplete at the end of its restart processing.
ADARUN PROG=ADANUC,DTP=TM,TMRESTART=FORCE
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime | Indicates whether or not the ATM manager is to interact with an external transaction coordinator. | NONE | RRMS | NONE |
The TMSYNCMGR parameter determines whether or not the ATM manager registers and interacts with an external transaction coordinator.
Possible values:
| Value | Description |
|---|---|
| NONE | The ATM manager will not interact proactively with an external transaction coordinator. This setting does not preclude the use of the CICS Syncpoint Manager, which interfaces directly with the ATM’s client proxy component and not with the ATM manager. |
| RRMS | The ATM manager will register with the IBM Recoverable Resource Management Services so that it can participate in transactions that involve other RRMS-enabled resource managers. This parameter value is valid only for z/OS systems in which RRS (a component of RRMS) is active. The current version of ATM offers participation in RRMS-coordinated two-phase commit for single-user, single-TCB batch applications and for applications running under Com-plete or IMS/TM. |
ATM registers with RRMS so that it can take part in transactions involving other RRMS-enabled resource managers.
ADARUN PROG=ADANUC,DTP=TM,TMSYNCMGR=RRMS
| Parameter Type | Use | Possible Values | Default |
|---|---|---|---|
| Runtime | Defines the first one or two characters of dynamically allocated Client IDs. | up to 2 alphanumeric characters | TM |
To aid interpretation of Adabas Online Services displays and diagnostic logs, the ATM manager dynamically allocates an 8-byte client identifier (TCID) for each client session that engages in transactional activity. These client identifiers are simply labels, and have no operational significance.
The format of a dynamically allocated TCID is
ppnnxxxx
—where
pp is the value of the TMTCIDPREF parameter, left-justified and with trailing blanks if required.
nn is the 2-byte binary ATM database ID.
xxxx is a 4-byte binary suffix. Suffixes are allocated in sequence and are reused. The first TCID to be allocated has a suffix of zeros.
ATM will assign dynamic TCIDs beginning with the string "DY".
ADARUN PROG=ADANUC,DTP=TM,TMTCIDPREF=DY
Caution:
Before you use Adabas Transaction Manager in a production
environment, the settings for Adabas runtime parameters should be reviewed and
modified as necessary according to the recommendations provided in this
section.
The ATM transaction manager tracks and coordinates all Adabas transactional activity. This includes:
OP,CL,ET,BT and
RE commands
The first change-type command (A1,E1,N1,
etc.) to each DTP=RM database modified in a
transaction
The originating client’s transaction manager client proxy forwards these commands to the transaction manager for scrutiny.
Furthermore, the transaction manager acts as a focal point for transactional activity for all Adabas activity within the system image. Consequently, there may be times when significant load is experienced. Therefore, for production running, ATM transaction manager needs to be configured to handle high levels of concurrent activity.
Some Adabas parameters need to be reviewed. In general it is usually appropriate to take the values set for the busiest Adabas database in the system and use at least those values. In any case, setting values high, and reviewing them later, after a successful period of operation, is a reasonable safety first approach for most parameters. The following table describes the most important parameters which should be reviewed, but all other parameters should be considered also.
| Adabas Parameter | Description |
|---|---|
NU |
For the ATM manager, the |
NC |
The command queue size for the transaction manager needs to be set for high levels of throughput. |
NAB |
For each concurrent activity a portion of the attached buffers is used. |
NT |
Some transactional activity can take more time to complete than a normal Adabas command (for example, coordinating multiple databases to complete a transaction safely), so the number of threads in the ATM manager should be higher than might be expected. |
TMLOG=NO |
Numerous I/O operations to the TM LOG dataset are
performed when the TMLOG parameter is set to
TMLOG=YES. In a busy system, the I/O rate for
TMLOG=YES will have a significant impact on performance;
in such cases, set TMLOG=NO for the ATM manager.
|
Before using Adabas Transaction Manager in a production environment,
remember also to review the client runtime controls for jobs and TP systems
that will use ATM. Pay particular attention to the setting of
NumberLogRecordEntries.
When the transaction manager is started, certain ADARUN parameter values are enforced. If other values are supplied through the DDCARD DD statement, they are ignored and overwritten by the values preset for the manager. The enforced parameter values include the following, although other parameters might also be affected:
FASTPATH=NO
PLXID=0
READONLY=NO
SMPID=0
SPT=NO
UTIONLY=NO
VISTA=NO