Parameter Description for CKPTDEF

CKPT1=

Specifies the status of the primary checkpoint data set (in DUPLEX mode) or the alternately-used primary data set (in DUAL mode) from which JES2 reads and writes the checkpoint record. If this data set resides on DASD, specify its name and volume serial number. If this data set resides on a coupling facility, specify its structure name.

This data set can be:

The only checkpoint data set defined (MODE=DUPLEX and DUPLEX=OFF) or (MODE=DUAL, INUSE=Yes, and CKPT2 INUSE=No)
Used as the primary data set backed up by a duplex data set (MODE=DUPLEX and DUPLEX=ON)
Used as one of two-alternately used checkpoint data sets (MODE=DUAL).

If neither data set (CKPT1 or CKPT2) is defined at initialization, the operator will be prompted for name and device information following initialization processing.

DSName=jxx...x

Specifies a 1- to 44-character name (hyphens (-) may be included for any character except the first) which is used as the name of the primary checkpoint data set. This data set is normally named SYS1.JESCKPT1, but you can provide another name if you prefer. For example, you would be naming it TESTING.HASPCKPT if you specified the following initialization statement:

    CKPTDEF    CKPT1=(DSN=TESTING.HASPCKPT,...)

The DSNAME= parameter and the VOLSER= subparameter are mutually exclusive with the STRname= parameter.

If you do not define a structure on the coupling facility to contain the checkpoint data sets, you must specify a data set name for either CKPT1 or CKPT2 or both. If you do not, JES2 enters the checkpoint reconfiguration dialog.

Modification: Operator response to reconfiguration dialog messages only if the data set is specified as not in use (INUSE=No).

Note: To avoid potential confusion, IBM suggests that the name specified here not match the DSNAME= parameter specification on the SPOOLDEF initialization statement.

STRname=jxx...x

Specifies the 1- to 16-character name of the coupling facility structure to be used for a checkpoint data set. This structure must have been defined in the coupling facility policy. The name can contain numeric, uppercase alphabetic, dollar sign ($), at sign (@), pound sign (#), or underscore (_) characters.

This subparameter is mutually exclusive with the DSNAME= and VOLSER= subparameters.

The STRname= parameter has no default; you must specify it to place a checkpoint data set in a structure on the coupling facility.

VOLser=xxxxxx

Specifies the volume serial number on which the data set specified by the DSName= parameter resides.

The DSNAME= parameter and the VOLSER= subparameter are mutually exclusive with the STRname= parameter.

Modification: Operator response to reconfiguration dialog messages only if the data set is specified as not in use (INUSE=No).

Performance Considerations: Because the checkpoint data set is frequently referenced, particularly in multi-access spool configurations, it should not be on any volume containing high-usage data sets. For example, performance can be seriously degraded if you allow all or part of SYS1.HASPACE (or the data set name specified on the DSNAME= parameter on the SPOOLDEF statement) to also reside on the volume containing SYS1.JESCKPTn (or the data set name specified on the DSName= parameter). Only low-usage data sets (if any) should be allocated on the same volume as the checkpoint data set.

Also, IBM suggests that you do not issue a RESERVE against a designated VOLser volume; this too will degrade system performance.

INUSE=Yes|No

Specifies whether this data set is defined to a JES2 multi-access spool configuration as a checkpoint data set. End of change

Modification: Operator response to reconfiguration dialog messages.

Note:

At least one checkpoint data set (CKPT1 or CKPT2) must be designated as INUSE=Yes in order that JES2 has a checkpoint data set to use.
Operating in DUAL mode (with alternating primary data sets) (MODE=DUAL) requires both CKPT1 and CKPT2 be specified as INUSE=Yes
Operating in DUAL mode (with only one primary data set) (MODE=DUAL) requires either CKPT1 or CKPT2 be specified as INUSE=Yes
Operating in DUPLEX mode (with a backup data set) (MODE=DUPLEX,DUPLEX=ON) requires both CKPT1 and CKPT2 be specified as INUSE=Yes
Operating in DUPLEX mode (without a backup data set) (MODE=DUPLEX,DUPLEX=OFF) requires either CKPT1 or CKPT2 be specified as INUSE=Yes

CKPT2=

Specifies the status of the duplex or alternately-used checkpoint data set for either:

The data set used as the back-up copy of the primary data set defined by CKPT1 (MODE=DUPLEX and DUPLEX=ON)
The second of two alternately-used checkpoint data sets (MODE=DUAL).

If this data set resides on DASD, specify its name and volume serial number. If this data set resides on a coupling facility, specify its structure name.

If CKPT2 is not defined at initialization, JES2 assumes that no backup checkpoint data set is required; the operator is not prompted to supply this information.

DSName=jxx...x

Specifies a 1- to 44-character name (hyphens (-) may be included for any character except the first) which is used as the name of the primary checkpoint data set.

If you do not define a structure on the coupling facility to contain the checkpoint data set(s), you must specify this data set name if the data set is required; JES2 will prompt the operator to supply a name only if this data set is in use.

The DSNAME= subparameter and the VOLSER= subparameter are mutually exclusive with the STRname= subparameter.

Modification: Operator response to reconfiguration dialog messages only if this data set is specified as not in use (INUSE=No).

Note:

If MODE=DUPLEX, CKPT2 is not used as a backup (duplex) data set to CKPT1 unless DUPLEX=ON is also specified or defaulted.
To avoid potential confusion, IBM suggests that the name specified here not match the DSNAME= parameter specification on the SPOOLDEF initialization statement.

STRname=jxx...x

This subparameter is mutually exclusive with the DSNAME= and VOLSER= subparameters.

The STRname= parameter has no default; you must specify it to place a checkpoint data set in a structure on the coupling facility.

VOLser=xxxxxx

Specifies the volume serial number on which the data set specified by the DSName= parameter resides.

You must specify this volume serial if it is required; however, JES2 will prompt the operator to supply this information if this data set is in use.

Modification: Operator response to reconfiguration dialog messages only if the data set is specified as not in use (INUSE=No).

Note: The volume serial number specified for CKPT2 need not be different from that specified for CKPT1.

INUSE=Yes|No

Specifies whether this data set is defined to a JES2 multi-access spool configuration as a checkpoint data set. End of change

Modification: Operator response to reconfiguration dialog messages.

Note: At least one checkpoint data set (CKPT2 or CKPT1) must be designated as INUSE=Yes in order that JES2 has a checkpoint data set to use.

CKPTOPT=HIGHEST|CKPT1|CKPT2

Specifies which checkpoint data set is to be used when JES2 is restarted.

CKPT1: Specifies that JES2 is to use the CKPT1 data set as the source of the checkpoint for building the JES2 work queues.
CKPT2: Specifies that JES2 is to use the CKPT2 data set as the source of the checkpoint for building the JES2 work queues.
HIGHEST: Specifies that JES2 is to determine which checkpoint data set contains the most recent checkpoint, and use that data set for building the JES2 work queues.

Modification: Hot start. This parameter will use the option specified when JES2 is started.

Note: This parameter must never be specified in the PARMLIB member where your installation's initialization statements are defined. It can only be entered during JES2 initialization while in CONSOLE mode. See z/OS JES2 Initialization and Tuning Guide for more details on CONSOLE mode.

DUPLEX=ON|OFF

Specifies whether duplexing is turned on (ON) or off (OFF). If DUPLEX=ON is specified or defaulted, you will be able to use the CKPT2 data set to replace the primary (CKPT1) checkpoint data set if that data set becomes unavailable.

If a checkpoint resides on a coupling facility structure, JES2 forces this parameter to MODE=DUPLEX.

Note:

DUPLEX=ON only has meaning if MODE=DUPLEX is also specified. That is, the entire multi-access spool configuration must be operating in DUPLEX mode, then you can set duplexing on or off for each individual member.
DUPLEX=ON need not be defined on each member of a multi-access spool configuration; however, it is recommended that you do so when operating in duplex mode. Those members that have turned duplexing off (DUPLEX=OFF) will not write to the backup checkpoint data set.
The DUPLEX value does not affect the CKPT1 or CKPT2 INUSE setting of the multi-access spool configuration.

Attention: If you specify MODE=DUPLEX and DUPLEX=OFF you have turned off checkpoint data set duplexing for this particular multi-access spool member; a backup copy of the checkpoint data set will not be maintained for this member. If you set DUPLEX=OFF on all members of the multi-access spool configuration, an I/O error occurring on CKPT1 can prove rather disastrous to the single-member or multi-access spool configuration if JES2 also fails.

Modification: $T CKPTDEF operator command.

LOGSIZE=nnnn

The LOGSIZE parameter specifies the number (1-4000) of 4K-blocks of storage used for the change log portion of the checkpoint data set.

Although JES2 allocates a change log for both DUPLEX or DUAL mode, the change log is only used in DUAL mode. JES2 computes a default value by the following algorithm:

If MODE=DUPLEX:

LOGSIZE=1

Note: Although JES2 allocates space for the change log when operating in DUPLEX mode, the change log is not actually used. If MODE=DUAL:

    If number of 4K-blocks that fit on TRACK1
of CKPT1>=1
                           and
       number of 4K-blocks that fit on TRACK1 of CKPT2>=1
                           then
    LOGSIZE= lesser of the number of 4K blocks that fit on
             CKPT1 and CKPT2

                           -- OR --

    If the number of 4K-blocks that fit on CKPT1<1
                           or
       number of 4K-blocks that fit on CKPT2<1
                           then
    LOGSIZE=1

Modification: Cold start or all-member warm start if RECONFIG is specified as an start option.

Performance Considerations: For increased performance, prevent the updates from overflowing the change log. If the used portion of the change log can be contained on the first track, it can be read at the same time as all the other records on track 1 during the READ1 portion of the checkpoint cycle. Trace ID 17 can provide data on the size of the active portion of the change log and assist your tuning of the size specification required here. See z/OS JES2 Diagnosis for more information on Trace ID 17.

MODE=DUAL|DUPLEX

Specifies whether the multi-access spool configuration will use the data set defined by CKPT2= as the alternate primary checkpoint data set (DUAL) or as the backup to the CKPT1 data set (DUPLEX).

DUAL

Specifies that the data set specified by CKPT2 be used as the alternate primary checkpoint data set. The two data sets, specified by CKPT1= and CKPT2= are used in a “flip-flop” alternating scheme. (See z/OS JES2 Initialization and Tuning Guide for a further discussion of DUAL mode processing.)

If any checkpoint data set resides on a coupling facility (STRname= is coded for CKPT1, CKPT2, NEWCKPT1, or NEWCKPT2), JES2 forces the MODE= parameter to DUPLEX.

DUPLEX

Specifies that the data set specified by CKPT2 be used as the backup to the primary checkpoint data set. The data set specified by CKPT1= is the primary checkpoint data set and the data set specified by CKPT2= is the backup (duplex) checkpoint data set. (See z/OS JES2 Initialization and Tuning Guide for a further discussion of DUPLEX mode processing.)

Note:

If you specify MODE=DUAL, the DUPLEX= specification is ignored.
If you specify MODE=DUPLEX and DUPLEX=OFF for a specific member of the multi-access spool configuration, that member will neither use nor allocate a backup (CKPT2=) checkpoint data set.
If you specify MODE=DUPLEX and DUPLEX=ON for a specific member of the multi-access spool configuration, that member will use the data set defined by CKPT2= as the backup checkpoint data set.
The MODE= parameter must be specified the same for all members of the multi-access spool configuration.
The MODE= parameter can be changed through Operator Command.

Performance Considerations: If you specify MODE=DUAL on CKPTDEF, also specifying HOLD=99999999 on the MASDEF statement causes performance degradation. If you must use HOLD=99999999 on MASDEF, be certain to also specify MODE=DUPLEX on CKPTDEF.

Modification: Operator command.

NEWCKPT1=

Specifies the checkpoint data set that can be used to replace the data set defined by CKPT1= should that data set experience an I/O error or otherwise be unavailable. If this data set resides on DASD, specify its name and volume serial number. If this data set resides on a coupling facility, specify its structure name.

If this data set is not defined, the operator can define it at the time it is needed either within the checkpoint reconfiguration dialog or by a $T CKPTDEF,NEWCKPT1={(DSName=,VOLser=) | (STRname=)} command.

Note: IBM highly recommends that you define this data set in your initialization data set. It is only defined by this statement; it is not allocated and therefore does not require any storage space until it is used.

If you do not specify a value for this parameter, a $D CKPTDEF,NEWCKPT1 operator command displays the following:

$HASP829 CKPTDEF  NEWCKPT1=(DSNAME=,VOLSER=)

DSName=jxx...x

Specifies a 1- to 44-character name (hyphens (-) may be included for any character except the first) which is to be used as the name of the backup checkpoint data set to the data set defined by CKPT1=.

You must specify that this checkpoint resides on either a coupling facility structure (STRname=) or on DASD (DSName= and VOLser=). If you do not specify either STR= or DSN= and VOL=, the operator will be prompted to supply a data set name, by the $HASP273/$HASP272 message pair.

The DSNAME= subparameter and the VOLSER= subparameter are mutually exclusive with the STRname= subparameter.

Modification: $T CKPTDEF operator command or cold start.

STRname=jxx...x

Specifies the 1-to 16-character name of the coupling facility structure to be used as a checkpoint data set. This structure must have been defined in the coupling facility policy. The name can contain numeric, uppercase alphabetic, dollar sign ($), at sign (@), pound sign (#), or underscore (_) characters.

This subparameter is mutually exclusive with the DSNAME= and VOLSER= subparameters.

The STRname= parameter has no default; you must specify it to place a checkpoint data set in a structure on the coupling facility.

Modification: $T CKPTDEF operator command or cold start.

VOLser=xxxxxx

Specifies the volume serial number on which the data set specified by the DSName= parameter resides.

If you do not define a structure on the coupling facility to contain the checkpoint data set(s), you must specify this volume name if you require a NEWCKPT1 data set. If you do not specify a volume name, when this data set is needed, the operator will be prompted to supply a serial number, by the $HASP273/$HASP272 message pair.

The DSNAME= parameter and the VOLSER= parameter are mutually exclusive with the STRname= parameter.

Modification: $T CKPTDEF operator command or cold start.

Note: The volume serial number specified for NEWCKPT1 need not be different from that specified for CKPT1, CKPT2, or NEWCKPT2 although if more than one checkpoint data set resides on the same volume your member may suffer performance degradation. (See z/OS JES2 Initialization and Tuning Guide for further data set placement information.) However, it is recommended that this volume be different from those volumes defined for either of the primary checkpoint (CKPT1 and CKPT2) data sets.

NEWCKPT2=

Specifies the checkpoint data set that can be used to replace the data set defined by CKPT2= should that data set experience an I/O error or otherwise be unavailable. If this data set resides on DASD, specify its name and volume serial number. If this data set resides on a coupling facility, specify its structure name.

If this data set is not defined, the operator can define it at the time it is needed either within the checkpoint reconfiguration dialog or by a $T CKPTDEF,NEWCKPT2=[(DSName=,VOLser=) | (STRname=)} command.

DSName=jxx...x

You must specify that this checkpoint resides on either a coupling facility structure (STRname=) or on DASD (DSName= and VOLser=). If you do not specify either STR= or DSN= and VOL=, the operator will be prompted to supply a data set name, by the $HASP273/$HASP272 message pair.

Modification: $T CKPTDEF operator command or cold start.

STRname=jxx...x

This subparameter is mutually exclusive with the DSNAME= and VOLSER= subparameters.

The STRname= parameter has no default; you must specify it to place a checkpoint data set in a structure on the coupling facility.

Modification: $T CKPTDEF operator command or cold start.

VOLser=xxxxxx

Specifies the volume serial number on which the data set specified by the DSName= parameter resides.

You must specify this volume name if you require a NEWCKPT2 data set. If you do not specify a volume name, when this data set is needed, the operator will be prompted to supply a serial number; which can then be done by responding to the $HASP273/$HASP272 message pair.

This subparameter is mutually exclusive with the STRname= subparameter.

Modification: $T CKPTDEF operator command or cold start.

Note: The volume serial number specified for NEWCKPT2 need not be different from that specified for CKPT1, CKPT2, or NEWCKPT1. However, it is recommended it be different from those volumes defined for either of the primary checkpoint (CKPT1 and CKPT2) data sets.

OPVERIFY=Yes|No

Specifies whether (Yes) or not (No) JES2 prompts the operator during the checkpoint reconfiguration to verify or alter the default reconfiguration action. This parameter only applies to I/O error conditions when a NEWCKPTn value is defined. The operator is not consulted if JES2 can connect (coupling facility) or allocate (DASD) the NEWCKPTn data set.

If you enable operator verification (OPVERIFY=Yes), JES2 prompts the operator during the checkpoint reconfiguration dialog entered by JES2 for I/O errors only to respond to message pairs $HASP273 and $HASP272 or $HASP278 and $HASP272.

$HASP273 JES2 CKPTn DATA SET WILL BE ASSIGNED TO NEWCKPTn dsname ON
         VOLUME volser
$HASP272 ENTER RESPONSE

                                  -or-

$HASP278 UNABLE TO LOCATE OR UNABLE TO USE CKPTn|NEWCKPTn dsname ON
         VOLUME volser DOES NOT EXIST OR IS NOT USABLE
$HASP272 ENTER RESPONSE

If the original member driving the checkpoint reconfiguration failed and a new member replaces it as the driving member, the OPVERIFY parameter no longer applies. JES2 notifies the operator and does not automatically forward members. Not forwarding members automatically can prevent cascading member failure, which would result in the loss of all checkpoint data in the MAS and require a JES2 cold start.

If you suppress operator verification (that is, if you specify OPVERIFY=NO), JES2:

Replaces the checkpoint data set with its replacement data set defined on the NEWCKPTn parameter of the CKPTDEF statement.
Creates a replacement checkpoint data set automatically when a NEWCKPTn setting cannot be located.
This new checkpoint data set is always defined on DASD. JES2 dynamically allocates a new coupling facility structure only if a structure policy has been defined; JES2 cannot create a structure policy even if the original checkpoint was defined as a coupling facility structure.

Note: If JES2 determines that the new checkpoint will reside upon a volatile coupling facility (regardless of the OPVERIFY=No and VOLATILE=(ALLCKPT=IGNORE) or VOLATILE=(ONECKPT=IGNORE) settings), the operator will be prompted to respond to message $HASP237.

Modification: $T CKPTDEF operator command or cold start.

RECONFIG=Yes|No

RECONFIG= Yes specifies that JES2 uses the checkpoint data sets defined in CKPT1 and CKPT2, regardless of what checkpoints had been used previously. You should specify Yes only for the following conditions:

A previously unavailable checkpoint data set becomes available.
A previously available checkpoint data set becomes unavailable.
Both checkpoint data sets become unavailable so that you must restart JES2 from an emergency checkpoint data set.

RECONFIG= NO instructs JES2 to use the checkpoint data sets specified in CKPT1 and CKPT2 to start checkpoint processing. If JES2 detects that CKPT1 and CKPT2 are not the most recent checkpoint data sets, JES2 uses the data sets specified in these two parameters to locate the most recent checkpoint data sets.

Note:

RECONFIG=Yes is only valid on an all-member restart.
This parameter must never be specified in the PARMLIB member where your installation's initialization statements are defined; it can only be specified in console mode.

VERSIONS=(NUMBER=nn[,WARN=mmm])

Provides information JES2 uses to create and manage copies, or versions, of the checkpoint data set to be made available to application programs.

NUMBER=nn: Specifies the maximum number of copies that JES2 will maintain. In Z2 mode, the number can be between 2 and 17 (inclusive). After Z11 mode is activated, it can be between 2 and 50 (inclusive). A number that is too low can result in an application program deciding to use a copy that does not contain the most recent checkpoint data.
Note: Use this parameter to increase the limit for the JNUM resource that is reported on the HASP050 message.

This parameter defaults to 0, indicating that JES2 will determine the maximum number of versions to maintain.

Modification: $T CKPTDEF operator command.

WARN=mmm

Specifies a threshold percentage (0-100) of the maximum number of copies (versions) that are in use. When the specified percentage is reached, JES2 alerts the operator through the $HASP050 message. If you do not want JES2 to issue a message, specify zero for this parameter.

This parameter defaults to 80.

Modification: $T CKPTDEF operator command

VOLATILE=

Specifies how JES2 should respond when a checkpoint data set that resides on a coupling facility enters the state where, if power to the coupling facility is lost, all data on the coupling facility is lost.

This parameter does not apply when a coupling facility structure becomes volatile during the checkpoint reconfiguration dialog.

Before modifying this parameter see z/OS JES2 Initialization and Tuning Guide.

ONECKPT={WTOR|DIALOG|IGNORE}

Specifies the action that should be taken if the coupling facility on which a checkpoint data set resides becomes volatile (unstable). JES2 uses the ONECKPT= subparameter settings if:

Only one of the two checkpoint data sets resides on a coupling facility structure, and that coupling facility has become volatile.
Both checkpoint data sets reside on a coupling facility, but only one becomes volatile.

WTOR: Specifies that JES2 issues a WTOR so the operator can determine whether to suspend or continue the use of the checkpoint data set that resides on a coupling facility structure.
DIALOG: Specifies that JES2 enters the checkpoint reconfiguration dialog if a coupling facility becomes volatile.
IGNORE: Specifies that JES2 ignores the volatile status of the coupling facility.

ALLCKPT={WTOR|DIALOG|IGNORE}

Specifies the action that should be taken if all available checkpoint data sets (INUSE=Yes) that reside on a coupling facility become volatile (unstable). If you have only one checkpoint residing on a coupling facility, JES2 uses the ALLCKPT subparameter settings.

WTOR: Specifies that JES2 issues a WTOR when all available checkpoints residing on coupling facilities become volatile, so the operator can determine whether to suspend or continue the use of the checkpoint(s).
DIALOG: Specifies that JES2 enters the checkpoint reconfiguration dialog if all available checkpoints residing on coupling facilities become volatile.
IGNORE: Specifies that JES2 ignores the volatile status of the coupling facility. JES2 ignores this action setting if ONECKPT=WTOR|DIALOG. Instead, JES2 uses the ONECKPT setting.

Modification: $T CKPTDEF operator command or cold start.