Memory Notification: Library Cache Object loaded into SGA
Heap size 97011K exceeds notification threshold (51200K)
Details in trace file /oracle/app/db/diag/rdbms/mdmdb/MDMDB1/trace/MDMDB1_ora_31499.trc
KGL object name :create table T$GB_10FE975E4A207B0BE053 nologging tablespace CMX_TEMP noparallel  as select 
2015-03-11 14:44:24.051000 +08:00
Memory Notification: Library Cache Object loaded into SGA
Heap size 96984K exceeds notification threshold (51200K)
Details in trace file /oracle/app/db/diag/rdbms/mdmdb/MDMDB1/trace/MDMDB1_ora_31499.trc
KGL object name :create table T$GC_10FE975E4A207B0BE053 nologging tablespace CMX_TEMP noparallel  as select 
2015-03-11 14:44:33.939000 +08:00
Memory Notification: Library Cache Object loaded into SGA
Heap size 96166K exceeds notification threshold (51200K)
Details in trace file /oracle/app/db/diag/rdbms/mdmdb/MDMDB1/trace/MDMDB1_ora_31499.trc
KGL object name :create table T$GV_10FE975E4A207B0BE053 nologging tablespace CMX_TEMP noparallel  as select 
2015-03-11 14:44:43.926000 +08:00
Memory Notification: Library Cache Object loaded into SGA

SELECT * FROM (
SELECT a.ksppinm AS parameter,
       a.ksppdesc AS description,
       b.ksppstvl AS session_value,
       c.ksppstvl AS instance_value
FROM   x$ksppi a,
       x$ksppcv b,
       x$ksppsv c
WHERE  a.indx = b.indx
AND    a.indx = c.indx
AND    a.ksppinm LIKE '/_%' ESCAPE '/'
ORDER BY a.ksppinm) 
WHERE parameter IN ('_kgl_large_heap_warning_threshold')

PARAMETER
--------------------------------------------------------------------------------
DESCRIPTION
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SESSION_VALUE
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
INSTANCE_VALUE
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
_kgl_large_heap_warning_threshold
maximum heap size before KGL writes warnings to the alert log
52428800
52428800

In the description of the parameter indicates: maximum heap size before KGL writes warnings to the alert log 

Workaround 
If you want to disappear the message from the alert.log increase the hidden parameter to something bigger, for example

ALTER SYSTEM SET "_kgl_large_heap_warning_threshold" = 99428800 SCOPE=SPFILE ;