SELECTEX

The SELECTEX call monitors a set of sockets, a time value, and an ECB. It completes when either one of the sockets has activity, the time value expires, or one of the ECBs is posted.

To use the SELECTEX call as a timer in your program, do either of the following tasks:

Set the read, write, and exception arrays to zeros.
Specify MAXSOC ≤ 0.

Table 1. SELECTEX call requirements
Condition	Requirement
Authorization:	Supervisor state or problem state, any PSW key.
Dispatchable unit mode:	Task.
Cross memory mode:	PASN = HASN.
Amode:	31-bit or 24-bit. Note: See the addressability mode (Amode) considerations under CALL instruction API environmental restrictions and programming requirements.
ASC mode:	Primary address space control (ASC) mode.
Interrupt status:	Enabled for interrupts.
Locks:	Unlocked.
Control parameters:	All parameters must be addressable by the caller and in the primary address space.

Figure 1 shows an example of SELECTEX call instructions.

Figure 1. SELECTEX call instruction example

If an application intends to pass a single ECB on the SELECTEX call, then the corresponding working storage definitions and CALL instruction should be coded as shown in the following example:

                                                        
WORKING-STORAGE SECTION.                               
    01  SOC-FUNCTION    PIC X(16)  VALUE IS 'SELECTEX'.
    01  MAXSOC          PIC 9(8)   BINARY.             
    01  TIMEOUT.                                       
        03  TIMEOUT-SECONDS    PIC 9(8) BINARY.        
        03  TIMEOUT-MINUTES    PIC 9(8) BINARY.        
    01  RSNDMSK         PIC X(*).                      
    01  WSNDMSK         PIC X(*).                      
    01  ESNDMSK         PIC X(*).                      
    01  RRETMSK         PIC X(*).                      
    01  WRETMSK         PIC X(*).                      
    01  ERETMSK         PIC X(*).                      
    01  SELECB          PIC X(4).                      
    01  ERRNO           PIC 9(8)   BINARY.             
    01  RETCODE         PIC S9(8)  BINARY.             
                                                       
Where * is the size of the select mask                 
                                                        
 PROCEDURE DIVISION.                                    
    CALL 'EZASOKET' USING SOC-FUNCTION MAXSOC TIMEOUT   
                    RSNDMSK WSNDMSK ESNDMSK             
                    RRETMSK WRETMSK ERETMSK             
                    SELECB ERRNO RETCODE.

However, if the application intends to pass the address of an ECB list on the SELECTEX call, then the application must set the high order bit in the ECB list address and pass that address using the BY VALUE option as documented in the following example. The remaining parameters must be set back to the default by specifying BY REFERENCE before ERRNO:

 WORKING-STORAGE SECTION.                               
     01  SOC-FUNCTION    PIC X(16)  VALUE IS 'SELECTEX'.
     01  MAXSOC          PIC 9(8)   BINARY.             
     01  TIMEOUT.                                       
         03  TIMEOUT-SECONDS    PIC 9(8) BINARY.        
         03  TIMEOUT-MINUTES    PIC 9(8) BINARY.        
     01  RSNDMSK         PIC X(*).                      
     01  WSNDMSK         PIC X(*). 
     01  ESNDMSK         PIC X(*).                    
     01  RRETMSK         PIC X(*).                    
     01  WRETMSK         PIC X(*).                    
     01  ERETMSK         PIC X(*).                    
     01  ECBLIST-PTR     USAGE IS POINTER.            
     01  ERRNO           PIC 9(8)   BINARY.           
     01  RETCODE         PIC S9(8)  BINARY.           
                                                      
 Where * is the size of the select mask               
                                                      
 PROCEDURE DIVISION.                                  
    CALL 'EZASOKET' USING SOC-FUNCTION MAXSOC TIMEOUT 
                    RSNDMSK WSNDMSK ESNDMSK           
                    RRETMSK WRETMSK ERETMSK           
                    BY VALUE ECBLIST-PTR              
                    BY REFERENCE ERRNO RETCODE.

* The bit mask lengths can be determined from the expression:

((maximum socket number +32)/32 (drop the remainder))*4