Concurrent Managers responsible for batch processing and report generation. In the oracle EBS has three important Concurrent Managers: Internal Concurrent Managers, Standard Manager and Conflict Resolution Manager.

Internal Concurrent Manager: The ICM (Internal Concurrent Manager) controls all of the other concurrent managers.
Standard Manager: The Standard Manager accepts any and all requests. It has no predefined specialization rules and is active all the time. It is not recommended to add specialization rules to the standard manager as it can cause problems.
Conflict Resolution Manager: The Conflict Resolution Manager resolves conflicts, such as request incompatibilities.

How to check concurrent manager running or not?
Log in to applications as System Administrator responsibility and navigate to the concurrent > manager > administration page and under the processes column if the target and actual column equal the same number (above 0) this means the managers are up and running.

How to Start / Stop Concurrent manager ?
If concurrent managers down, Use this syntax to start the concurrent managers from the command line:

adcmctl.sh start apps/apps

You stop the concurrent managers from the command line:

adcmctl.sh stop apps/apps

Location of adcmctl.sh Scripts is $COMMN_TOP/admin/scripts $CONTEXT_NAME/

Where the location of Concurrent Managers Log files?
The concurrent manager log files can be located in one of the following places:

1. If the environment variable $APPLCSF is set, the default location is $APPLCSF/$APPLLOG
2. If the environment variable $APPLCSF is not set, the logs go to $FND_TOP/$APPLLOG

NOTE: The default name of the concurrent manager log files is std.mgr. You can change these by setting the parameter logfile=.

Manager Log Files:

Standard manager log: w.mgr
Transaction manager log: t.mgr
Conflict Resolution manager log: c.mgr

Where: is the concurrent process id of the manager