IIS 8.5 w3wp.exe crash ntdll.dll

i'm on a Windows Server 2012 r2 and there is a problem with a website. Every ~6min a w3wp.exe of a specific website crash.

In Event Viewer i see:

Faulting application name: w3wp.exe, version: 8.5.9600.16384, time stamp: 
0x52157ba0
Faulting module name: ntdll.dll, version: 6.3.9600.18233, time stamp: 0x56bb4e1d
Exception code: 0xc0000374
Fault offset: 0x000e6054
Faulting process id: 0x3d88
Faulting application start time: 0x01d2f406c4d0b47a
Faulting application path: C:\Windows\SysWOW64\inetsrv\w3wp.exe
Faulting module path: C:\Windows\SYSTEM32\ntdll.dll
Report Id: 4c7498c7-5ffb-11e7-80d5-00155d324108
Faulting package full name: 
Faulting package-relative application ID:

In System Event viewer:

A process serving application pool 'www.websitename.com' suffered a fatal communication error with the Windows Process Activation Service. The process id was '16528'. The data field contains the error number.

I tried to use DebugDiag 1.2:

In w3wp__www.websitename.com__PID__24776__Date__07_03_2017__Time_11_32_35AM__939__First chance exception 0X04242420.dmp the assembly instruction at KERNELBASE!RaiseException+68 in C:\Windows\System32\KERNELBASE.dll from Microsoft Corporation has caused an unknown exception (0x04242420) on thread 7

Anyway are all generic errors.. how can i do a good debug? Thank you