DB2 Tablespace has no space SQLcode -960 SQLState=57011

Our application is inserting and updating records into a DB2 database. It's been running for about 3 years, and we encountered an error SQLcode -960 SQLState=57011 SQLERRMC=IS_SMALL_TS The tablespace details are as follows: Tablespace ID = 5 Name = IS_SMALL_TS Tуре =- Database managed space Contents = All permanent data. Large table space. State = 0x0000 Detailed explanation: Normal Total pages = 894976 Number of useable pages = 894972 Number of used pages = 893844 Number of free pages =1128 High water mark (pages) =893844 Page size (bytes) =16384 Extent size (pages) =4 Prefetch size (pages) =4 Number of containers =1 The Db2level info is as follows: D: \IBM\SQLLIB\BIN>db2level DB21085I This instance or install (instance name, where applicable: "DB2") uses "64" bits and DB2 code release "SQL11014" with level identifier 0205010F. Informational tokens are "DB2 v11.1.4050.859", "51911120160", DYN1911120100WIN64 , and Fix Pack "5". Product is installed at "D:\IBM\SQLLIB" with DB2 Copy Name "DB2COPY1". We read through IBM Manual and tried a few thing including Alter tablespace IS_SMALL_IS increase 30 percent but don't see any changes. What can we do?