IMS Version 9

START IRLMPROC

Format

Read syntax diagramSkip visual syntax diagram               .---------------------------------.
               V                                 |
>>-S irlmproc----+-----------------------------+-+-------------><
                 +-,DEADLOK='seconds#,cycles#'-+
                 +-,IRLMGRP=irlmds-------------+
                 +-,IRLMID=irlmid--------------+
                 +-,IRLMNM=irlmname------------+
                 +-,LOCKTAB=irlmlt1------------+
                 +-,MAXCSA=maxcsannn-----------+
                 +-,MAXUSRS=nnn----------------+
                 |      .-NO--.                |
                 +-,PC=-+-YES-+----------------+
                 |          .-YES-.            |
                 +-,PGPROT=-+-NO--+------------+
                 +-,SCOPE=-+-LOCAL----+--------+
                 |         +-GLOBAL---+        |
                 |         '-NODISCON-'        |
                 |         .-NO--.             |
                 '-,TRACE=-+-YES-+-------------'

Usage

The START irlmproc command starts an IRLM component with a procedure put in place by your installation. Symbolic parameters in the procedure can be overridden using the START irlmproc command. IRLM must be started before any IMS subsystem that needs the facilities provided by IRLM.

The irlmproc identifies the procedure name of the IRLM to be started.

Any IRLM parameter can be overridden using the START command.

DEADLOK=
Specifies the local deadlock-detection interval (in seconds), and the number of local cycles that are to occur before a global detection is initiated. You can specify the following:
seconds#
This 1- to 4-digit numeric value, ranging from 1 to 9999, specifies the interval (in seconds) between IRLM local deadlock-detection cycles. Although values above 5 are accepted, the maximum used is 5.

Recommendation: Set this parameter to be no greater than 5. This is because it takes multiple local cycles to complete one global cycle. Otherwise, global deadlocks may not be broken frequently enough to ensure maximum throughput.

cycles#
This 1- to 4-digit numeric value, ranging from 1 to 9999, specifies the number of local deadlock cycles that must expire before global deadlock-detection is performed. Although values above 1 are accepted, the maximum used is 1.

Recommendation:  Set this parameter to be no greater than 5. This is because it takes multiple local cycles to complete one global cycle. Otherwise, global deadlocks may not be broken frequently enough to ensure maximum throughput.

IRLMGRP=
Specifies the name of the z/OS Cross-System Coupling Facility (XCF) group for which this IRLM will serve as lock manager.
irlmds
The name of the XCF group.
IRLMID=
Specifies either a decimal number or a printable character that is used to distinguish between multiple IRLMs. The IRLM with the lowest ID value in the group becomes the global deadlock manager for the group. You must specify a unique name for every IRLM in the group. The total number of IRLMs that can be included in a group is not related to the value you specify; the total number is limited by your hardware, and may be lower than 255.

The irlmid can be either a one- to three-digit number ranging in value from 1 to 255, or a printable EBCDIC character. When you specify a character, you must surround the character with enough single quotes to permit IRLM to understand that this value is indeed a printable character. IRLM converts the character to an EBCDIC value between 1 and 255.

Because of the way that z/OS interprets quotes, you must use 7 quotes on either side of the character.

Example: If you want to specify the printable character 'D', you must specify IRLMID='''''''D'''''''.

IRLMNM=
Specifies the 1- to 4-byte z/OS subsystem name assigned to this IRLM.
LOCKTAB
Specifies the lock table to be used by the data sharing group specified in the GROUP parameter.
irlmlt1
Is the name of the lock table.
MAXCSA=
Specifies the maximum amount of CSA that IRLM is to use for its lock structures. In displays, this storage is called accountable storage because it is accountable to the value you set for MAXCSA. Use the accountable storage high water mark (AHWM) data from messages DXR100I and DXR121I to monitor IRLM's usage of common storage and as a basis for adjustments to the MAXCSA value.

This parameter must be specified as a 1 or 3-digit number from 1 to 999. This number indicates the number of megabytes of CSA storage that IRLM will use. If IRLM is using extended CSA support and running on a z/OS system, this number indicates multiples of 1 MB of extended CSA storage. For example, a specification of 3 states that IRLM can use 3 MB of CSA, or 3 MB of ECSA, if IRLM is running with extended CSA support on a z/OS system.

MAXUSRS=
Specifies the maximum number of users, from 2 to 248, that can connect to the data sharing group.
PC=
Specifies whether a space switching program call is to be used by IRLM. If PC=YES is specified, the IRLM lock control block structure resides in the IRLM address space, and the space switching program call (PC) instruction is used to obtain addressability to the structure. If PC=NO is specified, the IRLM lock structure resides in ECSA. The default for this parameter is PC=NO. Tells IRLM whether to place its COMMON STORAGE load modules into z/OS Page Protected Storage. PGPROT=YES is the DEFAULT and tells IRLM to place its COMMON Storage load modules into z/OS Page Protected Storage. If PGRPROT=NO is specified, IRLM will not place load modules in Page Protected Storage.
SCOPE=
Specifies whether the IRLM is to be used in a data-sharing environment and, if so, whether the IRLM should automatically disconnect when the associated IMS terminates.
LOCAL
Specifies that the IRLM is in a non-data-sharing environment and there is no intersystem sharing.
GLOBAL
Specifies that the IRLM is in a data-sharing environment and that intersystem sharing is to be performed. The IRLM disconnects from the data-sharing group when there are no IMSs identified to it. Both XCF and SLM are required
NODISCON
Specifies that the IRLM is in a data-sharing environment and that intersystem sharing is to be performed. The IRLM remains connected to the data-sharing group even when there are no IMSs identified to it. Normal DISCONNECT from the sharing group does not occur. You must explicitly stop the IRLM when NODISCON is specified. Both XCF and SLM are required.

With NODISCON, there is less impact on other systems when an IMS fails because z/OS is not required to perform certain recovery actions that it normally perform when an IRLM terminates. Another benefit of the NODISCON parameter is that IMS restarts more quickly after a normal or abnormal termination because it does not have to wait for IRLM to rejoin the IRLM data-sharing group.

TRACE=
Specifies whether the IRLM should trace activity during IRLM startup. Traces are written to wrap-around trace buffers, that is, the first buffer is reused after the last buffer is full.
NO
Do not initialize trace activity during IRLM startup. NO is the default.

To trace IRLM activity, use the TRACE CT command. See TRACE CT

YES
Initialize IRLM trace activity during startup.

Recommendation:  Turn on tracing in all data-sharing environments.

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Copyright: IBM Corporation 1974, 2004 Copyright IBM Corporation 1974, 2004  timestamp Last updated: March, 2004