It is possible for all the methods listed in Methods available for specifying runtime options to be used for a given application. The order of precedence (from highest to lowest) between option specification methods is:

1. Options specified on invocation of the application (or in the case of an application invoked by one of the exec or spawn family of functions, options specified in the environment variable _CEE_RUNOPTS).
2. Options specified at invocation time through a DD card (DD:CEEOPTS). The CEEOPTS DD is ignored for programs invoked using one of the exec() family of functions.
3. Options specified in a CELQUOPT CSECT. There are a few methods available to provide a CELQUOPT CSECT:
   • Assemble a CELQUOPT. For more information, see Creating application runtime option defaults with CEEXOPT.
   • Specify the C/C++ #pragma runopts() directive within a source program. The compiler generates the CELQUOPT CSECT from the given options.

   If you select #pragma runopts(), specify it in one and only one compile unit in the application; for example, in the main routine. If multiple CELQUOPTs are present, binder input ordering determines which CELQUOPT is used in an executable program. Only the first CELQUOPT CSECT linked in an executable program is applied. The binder treats any subsequent CELQUOPTs seen in the input as duplicates and they will be ignored.

4. Region-level default options defined within CELQROPT.
5. System-level default options changed after IPL with a SETCEE command.
6. System-level default options changed after IPL with a SET CEE command.
7. System-level default options set in a CEEPRMxx parmlib member and identified during IPL by a CEE=xx statement. This statement can be specified either in the IEASYSyy data set or in the IPL parameters.
8. IBM-supplied defaults.

When the non-overrideable (NONOVR) attribute is specified for a runtime option, all methods of specifying that runtime option with higher precedence are ignored.

IBM-supplied default   IOHEAP64=((1M,1M,FREE,12K,8K,FREE,4K,4K,FREE),OVR)
CEEPRMxx used at IPL   IOHEAP64=((1M,1M,FREE,4K,4K,FREE,4K,4K,FREE),OVR)
CELQUOPT               IOHEAP64=(,,KEEP)

Used at runtime        IOHEAP64(1M,1M,KEEP,4K,4K,FREE,4K,4K,FREE)