How many Actual and Target processes do you have defined for the Standard Manager? Look in System Administrator->Concurrent->Administer, then adjust Work Shift->Processes in Concurrent->Define.
BTW, if you make the processes 200, so 200 requests run in parallel, you may overload your database server. How long do these requests all take to run?
We have 30 actual & target processes for Standard Manager and 60 Sleep seconds.
You mean, 30 managers are available/free ; But only 4 requests are running at a time and remaining managers are idling ?
1. Please go through AWR report (for 60 min interval) during the problematic period. This is to check any expensive DML/Query in the system (or) Concurrent Manger sub-system.
2. Please go through the output of bde_chk_cbo.sql as per note 174605.1 to check whether init.ora are in tact.
Are they actually getting picked up by the Standard Manager? If you really want to have 200 jobs run at the same time then I would recommend putting them on a separate manager, otherwise (depending on how long they run for) you risk flooding the standard manager and holding up other jobs that are waiting to run.