Package

A package is the executable form of one DBRM after it has been bound. It is the unit DB2 actually runs.

What is a package

• A package is created by BIND PACKAGE from a single DBRM.
• It stores the access paths chosen by the DB2 optimizer for that program's SQL statements.
• Packages are stored in the DB2 catalog (SYSIBM.SYSPACKAGE). They are not PDS members.
• Each package carries a consistency token that must match the program's load module at run time.

Why packages are used

• Bind each program's DBRM separately instead of rebinding one giant plan.
• When one program changes, rebind only its package. The other programs are untouched.
• The same package can be listed in the PKLIST of many different plans.
• Different versions of a program can live side by side in different collections (next page).

Package vs plan - quick comparison

• Package = the bound form of one program's SQL.
• Plan = the bound control structure that points to packages (or DBRMs).
• A program always runs under a plan. The plan finds the program's package at run time.
• Small shops often bind DBRMs straight into a plan. Larger shops use packages plus collections.

Example: BIND PACKAGE control cards

• These DSN subcommands bind the DBRM member PROG1 into collection MYCOLL:
  
  DSN SYSTEM(DB2A) BIND PACKAGE (MYCOLL) MEMBER (PROG1) LIB ('USERID.DBRMLIB') QUALIFIER (APPOWN) ISOLATION (CS) EXPLAIN (NO) END