After determining that an application will execute under ETSO, sites should evaluate the impact of that application on their environment.
The following guidelines should be taken into consideration before a site allows an application to run under ETSO.
- Can CA Roscoe facilities perform the task instead or running an application under ETSO?
- Roscoe is not TSO. Applications which rely on TSO control blocks may not execute as expected under ETSO. Any questions about an application or problems encountered with an application should be directed to CA Support.
- CA Roscoe cannot make an application use fewer resources than it already does. An application requiring 100K to execute under TSO, for example, still requires 100K to execute under Roscoe. Certain efficiencies are gained, however, if the application is reentrant. In this case, only one copy of the application need be loaded into the Roscoe address space. Multiple users can concurrently execute the same reentrant application.
- An application written through a special facility needs that facility to execute under Roscoe. For example, an application written with the IBM Program Development Facility (PDF) requires ISPF/PDF to execute under Roscoe. The same amount of space ISPF/PDF requires in TSO is required in Roscoe.
- An address space has a finite amount of memory. The resources required for an application to execute under ETSO come from the Roscoe address space. While ETSO enables a site to control through the EPL the CPU time and memory allocated to an application, these resources are not unlimited.
Sites can use the following formulas when deciding what applications to allow under ETSO:
- Determine the amount of memory available.
X = A - B - C
A Size of CA Roscoe address space.
B Amount of space required by CA- Roscoe.
C Amount of space required by the applications already allowed under ETSO.
- Determine the amount of memory required by the application.
Y = D + (E * F)
D Amount of space required by the application, provided the application is re-entrant.
E Amount of dynamic working storage (GETMAIN) required.
F Number of users expected to concurrently execute the application.
- If the amount of space required by the application is greater than that available, site management might consider:
- Omitting the application from ETSO.
- Determining if they can accept fewer concurrent users. (The more people concurrently executing an application, the greater the resource usage.)
- Executing a second Roscoe that is in whole or in part dedicated to ETSO applications. Since the Roscoe library system can (and should) be shared, user profile information and library members are available to both Roscoe's.