CALL instruction application programming interface (API)

This information describes the CALL instruction API for TCP⁄IP application programs written in the COBOL, PL/I, or System/370 Assembler language. The format and parameters are described for each socket call.

Notes:

Unless your program is running in a CICS® environment, reentrant code and multithread applications are not directly supported by this interface. Each task or thread needs to invoke its own copy of EZASOKET.
Modules that use EZASOKET must be non-reusable (NREUS) or serially reusable (REUS). If the module can be invoked again after its original task ends, the application needs to perform the TERMAPI call at the end of its function. Otherwise, unpredictable results are produced.
For a PL/I program, include the following statement before your first call instruction.
```
  DCL EZASOKET ENTRY OPTIONS(ASM,INTER) EXT;
```
If you use the CALL instruction from code that will run as a part of a CICS transaction, see the z/OS Communications Server: IP CICS Sockets Guide for additional considerations.
The Sockets Extended module (EZASOKET) is located in the hlq.SEZATCP(EZASOKET) load module and should be resolved from there when it is processed by the binder. You can use the linkage editor MAP parameter to produce the module map report to verify where EZASOKET is resolved.