Detector collection ended because of storage shortage along with message PDT0171

Products

• Detector for DB2 for z/OS

Issue/Introduction

Executing Detector for Db2 for z/OS (PDT) and noted the following message within Xmanager related to storage shortage:

PDT0171 DETECTOR COLLECTION INTERVAL END FORCED DUE TO XMANAGER STORAGE SHORTAGE, DB2=ssid

Resolution

Although Xmanager works with 64-bit storage above the bar, it is still possible to get error message PDT0171 if the Xmanager JCL startup does not have the appropriate parameters.

With Xmanager and REGION=32M you have to define the storage above the bar with parameter MEMLIMIT. MEMLIMIT can be explicitly set in the Xmanager JCL and should be at least 4G.

//XMANAGER EXEC PGM=PXMINICC,MEMLIMIT=xG

With REGION=0M then MEMLIMIT defaults to NOLIMIT. But MEMLIMIT=NOLIMIT is not recommended. If there is a problem allocating storage in the Xmanager address space then you will encounter problems because a lot of storage above the bar (64-bits) might be allocated without sense. So the recommended values are REGION=0M and MEMLIMIT a value between 4G and 8G.

For example in a large installation, 4G may not be enough and it is possible that PXM0372 message can be issued under normal conditions.

PXM0372 XMANAGER REGION INUSE HAS REACHED SHORTAGE THRESHOLD FOR type

Additionally you can specify values for CUSH64(low,high), CUSH64 controls Xmanager monitoring of 64-bits storage usage. With a value of MEMLIMIT under 4G, CUSH64(20,50) should be fine.
When the high limit is reached, you should see PXM0372 message issued and both Detector and Subsystems Analyzer will terminate active collections. When the low limit is reached, you should see PXM0371 and PXM0370 messages and Xmanager will shut itself down.

Keep in mind as well the storage for REGION and MEMLIMIT parameters can be restricted by a IEFUSI exit> Values in this exit have to be set accordingly
and allow Xmanager to work with 64-bits storage.