A stored procedure is an application program that runs in the DB2 LUW Server's address space. It can contain most statements that an application program normally contains. It can consist of more than one program. Your stored procedure can call other programs as well as nested stored procedures but there are restrictions.
The application program that invokes the stored procedure can be in any language that supports SQL statements. You can write a stored procedure using many languages such as C, Java, COBOL or now SQL Procedure Language which is consistent with the Persistent Stored Module definition of the ANSI SQL99 standard.
The store procedure can be written in one language, for example Java, with the client written in another language, for example COBOL. When the languages differ, DB2 transparently passes the values between the client and the stored procedure so each program gets the values in the expected format defined by the CREATE PROCEDURE statement.