Applications that use ICSF callable services must meet these invocation requirements:

• All output parameters must be in storage that the caller is allowed to modify in their execution key.
• All input parameters must be in storage that the caller is allowed to read in their execution key.
• Data can be located higher or lower than 16Mb but must be 31-bit addressable.

  Data can be located above 2Gb if the service is invoked in AMODE(64)

• Problem or supervisor state
• Any PSW key
• Task mode or Service Request Block (SRB) mode
• No mode restrictions
• Enabled for interrupts
• No locks held

The exceptions to this list are documented with the individual callable services.

All ICSF callable services support invocation in AMODE(64). Applications which are written for AMODE(64) operation must be linked with the ICSF 64-bit service stubs, and must invoke the service with the appropriate service name. (Refer to the description of the individual callable service to determine the service name to be used.)