Errors in the routine could damage VTAM® or system control blocks and modules. Consider the following restrictions when writing this routine:

• The name of the generic resource resolution exit routine module should be ISTEXCGR. However, if you have written an alternate load module, use the load module name that you assigned to your replacement module.
• This routine operates enabled in pageable storage. Because the routine operates at the VTAM main task dispatching priority, there is a possibility of lockout if a wait requires other task action. The routine gains control in supervisor state with a VTAM storage key. Errors within the routine could cause damage to VTAM or system control blocks and modules
• Do not issue any supervisor calls (SVCs) if this exit routine is running in service request block (SRB) mode.
• System waits, including implied waits for I/O operations, are not permitted. System waits cause VTAM failure in some situations that depend on timing.
• This exit routine should use only conditional storage invocations. You can reduce the possibility of a VTAM abend during a storage shortage by coding conditional storage invocations.
• Data is addressable in 31-bit mode only. The addresses of the data in the exit are 31-bit addresses.
• An abend of this exit routine causes VTAM to abend.
• This exit routine can reside above or below the 16-megabyte address.
• You must link-edit your routine into the appropriate library. See Installing VTAM exit routines for more information.
• This exit routine operates as an internal VTAM routine. VTAM performance might be degraded if the routine requires lengthy processing time. While this routine has control, VTAM does not process any new operator requests, session initiation requests, or session termination requests for any resource.