Formatting a system dump using the keyword XM=1 provides a number of transaction manager summaries that are useful for identifying why tasks have failed to run.
A task may fail to run if the system is at MXT, or if the task is defined in a transaction class that is at its MAXACTIVE limit.
Tasks can fail to run if either of the following limits is reached:
If a task is waiting for entry into the MXT set of transactions, the resource type is MXT, and the resource name is XM_HELD. If a task is waiting for entry into the MAXACTIVE set of transactions for a TCLASS, the resource type is TCLASS, and the resource name is the name of the TCLASS that the task is waiting for.
If a task is shown to be waiting on resource type MXT, it is being held by the transaction manager because the CICS system is at the MXT limit. The task has not yet been attached to the dispatcher.
The limit that has been reached, MXT, is given explicitly as the resource name for the wait. If this type of wait occurs too often, consider changing the MXT limit for your CICS system.
The transaction summary (Figure 13) lists all transactions (user and system) that currently exist. The transactions are listed in order of task number and the summary contains two lines per transaction.
The meanings of the column headings are as follows:
Depending on the value in the first line, the second line of the status field may further qualify the transaction state. For each first line value, the meaning of the second line is as follows:
The first word of this token contains the address of the TCA (if any) associated with the transaction.
Figure 13 shows a transaction summary.
==XM: TRANSACTION SUMMARY
Tran Tran TxnAddr Start Sys Status DS Facility Facility AP PG XS US RM SM
id num TxdAddr code Tran token type token token token token token token token
-----------------------------------------------------------------------------------------------------------------------
CSTP 00003 10106200 C Yes ACT 00120003 None n/a 10164600 00000000 00000000 00000000 1016C000 10089020
101793C0 01000000 1017E000 00000000 00000000 10164600 00000000
CSNE 00031 10106100 C Yes ACT 00000003 None n/a 10164C00 00000000 00000000 00000000 1016C058 11542054
10A34B40 01000000 1017E048 00000000 00000000 10164C00 00000000
IC06 10056 10E2B200 T No ACT 089601C7 Terminal 10E167A0 1124F600 00000000 00000000 10114023 1016C9A0 11543610
10AC9300 00000000 00000000 1017E7E0 00000000 10E0F6A0 1124F600 00000000
IC12 10058 10E34C00 SD No ACT 050601AD None n/a 001DE600 00000000 00000000 10114023 1016C9F8 11545114
10AC93C0 00000000 1017E828 00000000 10E31400 001DE600 00000000
TA03 93738 10E0E000 T No ACT 088211E3 Terminal 10ED9000 0024B000 00000000 00000000 10114023 1016C738 115437B0
10AD3D40 00000000 00000000 1017E090 00000000 10117D60 0024B000 00000000
TA03 93920 10AFF200 T No TCL 00000000 Terminal 11214BD0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3D40 DFHTCL03 00000000 00000000 00000000 00000000 10117680 00000000 00000000
TA03 93960 10E2D200 T No TCL 00000000 Terminal 10E573F0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3D40 DFHTCL03 00000000 00000000 00000000 00000000 10E0F6C0 00000000 00000000
TA03 93967 10AFEA00 T No TCL 00000000 Terminal 10ECCBD0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3D40 DFHTCL03 00000000 00000000 00000000 00000000 10117540 00000000 00000000
TA03 94001 10E34800 T No ACT 00000000 Terminal 10E2C3F0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3D40 DF(AKCC) 00000000 00000000 00000000 00000000 10E31120 00000000 00000000
TA02 95140 10E2D300 T No ACT 0386150D Terminal 10E2C5E8 00057000 00000000 00000000 10114023 1016C790 11544754
10AD3C80 00000000 00000000 1017E510 00000000 10E0F320 00057000 00000000
TA02 95175 10E12C00 T No TCL 00000000 Terminal 10E937E0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3C80 DFHTCL02 00000000 00000000 00000000 00000000 10E0F100 00000000 00000000
TA02 95187 10E0B000 T No TCL 00000000 Terminal 10EA95E8 00000000 00000000 00000000 10114023 00000000 00000000
10AD3C80 DFHTCL02 00000000 00000000 00000000 00000000 10117800 00000000 00000000
TA02 95205 10E2D600 T No MXT 00000000 Terminal 10E837E0 00000000 00000000 00000000 10114023 00000000 00000000
10AD3C80 DF(AKCC) 00000000 00000000 00000000 00000000 10E0F780 00000000 00000000
TA04 96637 10E33000 T No ACT 060408E7 Terminal 10E05BD0 00057600 00000000 00000000 10114023 1016C7E8 115457C8
10AD3E00 00000000 00000000 1017E558 00000000 10E31040 00057600 00000000
TA04 96649 10E34000 T No TCL 00000000 Terminal 10AE89D8 00000000 00000000 00000000 10114023 00000000 00000000
10AD3E00 DFHTCL04 00000000 00000000 00000000 00000000 10E312C0 00000000 00000000
F121 99305 10E2D800 T No ACT 020C1439 Terminal 10EA93F0 00060000 00000000 00000000 10114023 1016C898 115423FC
10AD3BC0 AB(AFCY) 00000000 00000000 1017E708 00000000 10E0F920 00060000 00000000
TS12 99344 10AFED00 T No MXT 00000000 Terminal 10E499D8 00000000 00000000 00000000 10114023 00000000 00000000
10AD6B40 00000000 00000000 00000000 00000000 101178C0 00000000 00000000
Notes for Figure 13
The MXT summary indicates whether CICS is currently at MXT and shows the current number of queued and active transactions. To check the status of an individual transaction, consult the main transaction summary (Figure 13).
==XM: MXT SUMMARY
Maximum user tasks (MXT): 7
System currently at MXT: Yes
Current active user tasks: 7
Current queued user tasks: 2
* Peak active user tasks: 7
* Peak queued user tasks: 2
* Times at MXT limit: 1
* NOTE: these values were reset at 18:00:00 (the last statistics interval collection)
The transaction class summary lists each transaction class that is currently installed. For each class, the current number of active and queued transactions is shown. A transaction class is at its MAXACTIVE limit if its ‘current active’ total is greater than or equal to its ‘max active’ setting. If a transaction class is at its MAXACTIVE limit, a number of transactions may be queueing in that transaction class. The transaction id and number of each queued transaction is listed with its transaction class (for example, transaction classes DFHCTL01, DFHCTL02, and DFHCTL03 in Figure 14).
==XM: TCLASS SUMMARY
Tclass Max Purge Current Current Total Queuing Queuing Queuing
Name Active Threshld Active Queued Attaches TranNum Transid Start Time
-------- -------- -------- -------- -------- -------- ------- ---- ------------
DFHTCL01 1 0 0 0 0
DFHTCL02 1 3 1 2 7 95175 TA02 18:00:19.677
95187 TA02 18:00:24.624
DFHTCL03 1 4 1 3 29 93920 TA03 17:55:40.584
93960 TA03 17:55:42.230
93967 TA03 17:55:52.253
DFHTCL04 1 0 1 1 23 96649 TA04 18:06:04.348
DFHTCL05 1 0 0 0 0
DFHTCL06 1 0 0 0 0
DFHTCL07 1 0 0 0 0
DFHTCL08 1 0 0 0 0
DFHTCL09 1 0 0 0 0
DFHTCL10 1 0 0 0 0
*** Note that the 'Total Attaches' figures were reset at 18:00:00 (the last statistics interval collection)
If you have found that a user task is waiting on a resource type of FOREVER, and resource name DFHXMTA, transaction manager has detected a severe error during task initialization or task termination. Transaction manager has suspended the task.
The suspended task is never resumed, and holds its MXT slot until CICS is terminated. You must cancel CICS to remove this task as you will be unable to quiesce the system. You cannot purge or forcepurge the task.
This wait is always preceded by one of the following messages: DFHXM0303, DFHXM0304, DFHXM0305, DFHXM0306, DFHXM0307, DFHXM0308, DFHXM0309, DFHXM0310. Transaction manager also takes a dump and message DFHME0116 is produced and contains the symptom string.
The suspended transaction has attempted to update the transaction definition identified by the transaction ID but found it already locked by another transaction.