A global application pool is used for modules that are needed in several applications, e.g. formats, connection module for formatting, database connection module, language runtime modules, shareable data areas, and also routines in program units and the message module.
A global application pool is set up by the first task of the first UTM application. All subsequent tasks of the same and other applications can connect to this pool, i.e. the pool is created with SCOPE=GLOBAL in the context of BS2000 system‘s memory pool management.
A global application pool offers similar advantages to a local application pool; however, the disadvantage is that the programs loaded in a global application pool cannot be exchanged dynamically while the application is running.
If global common memory pools of the same content/name are used in several UTM applications, the PAGE=X’xxxxxxxx’ parameter in the KDCDEF statement MPOOL must be specified with the same address in all applications. The address specified with PAGE= must be chosen such that the reserved address area is available in all of these applications.
Example
Application 1 uses the global pool MPONE. Application 2 also uses this pool in addition to pool MPTWO. The following KDCDEF control statements are required:
UTM generation application 1:
MPOOL MPONE, SCOPE=GLOBAL, PAGE=X’01000000’, SIZE=...
UTM generation application 2:
MPOOL MPTWO, SCOPE=GLOBAL, SIZE=...
MPOOL MPONE, SCOPE=GLOBAL, PAGE=X’01000000’, SIZE=...
As an alternative to using PAGE=, the shared pools can be generated in the same sequence in all applications. Moreover, these MPOOL statements must be the first MPOOL statements to be specified.