POSIX

Derivation: Portable Operating System Interface - X

POSIX specifies if the enclave can run with the POSIX semantics. POSIX is an application characteristic that is maintained at the enclave level. After you have established the characteristic during enclave initialization, you cannot change it.

The default value for non-CICS applications is POSIX(OFF).

POSIX is ignored under CICS®.

The default value for AMODE 64 is POSIX(ON).

Read syntax diagramSkip visual syntax diagram
Syntax

             .-OFF-.      
>>-POSix--(--+-----+--)----------------------------------------><
             '-ON--'      
OFF
Indicates that the application is not POSIX-enabled.
ON
Indicates that the application is POSIX-enabled.

Usage notes

  • When you set POSIX to ON, you can use functions that are unique to POSIX, such as pthread_create().
  • POSIX(ON) applies to z/OS but explicitly excludes CICS. If you set POSIX to ON while an application is running under CICS, you receive a warning message, POSIX is set OFF, and the application continues to run. You can specify POSIX(ON) for both DB2® and IMS™ applications.
  • When you set POSIX to ON while an application is running under CICS, you receive a warning message, POSIX is set OFF, and the application continues to run.
  • One of the effects of POSIX(ON) is the enablement of POSIX signal handling semantics, which interact closely with the Language Environment condition handling semantics.
  • ANSI C programs can access the z/OS® UNIX file system on MVS™ independent of the POSIX setting. Where ambiguities exist between ANSI and POSIX semantics, the POSIX runtime option setting indicates the POSIX semantics to follow.
  • Within nested enclaves, only one enclave can have the POSIX option set to ON. All other nested enclaves must have the POSIX option set to OFF. When a second nested enclave tries to specify the runtime option POSIX(ON) within one Language Environment process, Language Environment ends with abend U4093, reason code 172.

For more information

For more information about POSIX functions that have a kernel dependency or a POSIX ON dependency, see z/OS XL C/C++ Runtime Library Reference.

Parent topic: Using the Language Environment runtime options