How large can the size of the Datacom TTM be

Products

• Datacom/DB
• Datacom
• DATACOM - AD
• Datacom/AD

Issue/Introduction

Increasing  the size of the Datacom TTM area. How large can the TTM be? 

What is the impact to the LPAR if the TTM value is too large?

Environment

Release: 15.1

Resolution

The size of the TTM depends on the size of the SQL queries in the that MUF.
If 64-bit memory is available it can be as high as 19G, see documentation section VIRTUAL.
The higher the value the more 64-bit memory that is allocated. This can lead to paging when it is used. This would only happen while the query is running and using the TTM.

The size of the TTM can be increased permanently with the VIRTUAL startup parameter:
VIRTUAL    TTM017,7G,2G,3     TEMP WORK AREA FOR SQL REQUESTS  

This will allocate 7G initially and if it becomes full it will allocate another 2G three times.

To increase the TTM without restarting the MUF use the console command VIRTUAL_DYNAMIC_EXTEND, see article Increase VIRTUAL TTM size to avoid -560

Additional Information

See article Determining the amount of TTM blocks in use.