IBM Newly accessed tables result in increasing of dbheap - United States  TECHNOTE (TROUBLESHOOTING)

PROBLEM(ABSTRACT)
 Newly accessed tables result in increasing of dbheap 

SYMPTOM
From output of command "db2pd -db <db name> -mempools" you can find LogSz/PhySz of the memory pool named "dbh" keeps on increasing.


CAUSE
This is expected result. Every newly accessed table loads the tcb and has associated allocations for data, index, lob, compression dictionaries if applicable. This memory allocation is persistent/cached until the database deactivates or the table is dropped.

DIAGNOSING THE PROBLEM
Collect "db2pd -db showdb -memblocks 2 sort -alldbp", you will find most of the the newly memory allocations are from File 1601762203 LOC 1025 and LOC 1015: 

Day 1:

All memory consumers in Database memory set:
PoolID PoolName TotalSize(Bytes) %Bytes TotalCount %Count LOC File 
2 dbh 2502313088 51.03 59601 7.42 1025 1601762203
2 dbh 1906996352 38.89 59601 7.42 1015 1601762203
2 dbh 325096960 6.63 169321 21.08 2225 1235116617
2 dbh 37055232 0.76 159296 19.84 3159 1235116617

Day 2:

All memory consumers in Database memory set:
PoolID PoolName TotalSize(Bytes) %Bytes TotalCount %Count LOC File 
2 dbh 2642441600 50.76 63266 7.16 1025 1601762203
2 dbh 2027344256 38.95 63266 7.16 1015 1601762203
2 dbh 356836992 6.86 185844 21.03 2225 1235116617
2 dbh 40057088 0.77 174834 19.78 3159 1235116617

Note, for different versions, LOC might be different, above LOC only applies to V9.7FP11.

Collect "db2pd -d showdb -tcbstats -alldbp", you will see the number of tcb entries also keeps on increasing.





RESOLVING THE PROBLEM
This is the expected result, once all tables in the database are accessed for at least one time, the memory increasing will stop.
Why dbheap memory keeps increasing when I am running select count(*) for each table in my BLU database? 

I am running DB2 V11.1. It is a BLU database size of about 70T, most of the tables are column organized. I run select count(*) for each table, and finally got out of memory for dbheap. My question is:

    How to release the data in dbheap.

This memory allocation is persistent/cached until the database deactivates or the table is dropped.