text: **11.5.1 User exit header file (arscsxit.h)**
  
  Before you write the user exit, it is important to study the header file arscsxit.h. This file is in 
  the same exits directory as the sample user exit source code. This file contains the structure 
  and function declarations for the customized Content Manager OnDemand user exits. Also, 
  instructions are included to activate the user exit after it is compiled. 
  
  The first part of the header file is a declaration of all of the structures and variables that are 
  used. Example 11-9 shows several of the common structures that are used in the functions 
  declarations. 
  
  *Example 11-9 Common structure that is defined in the arscsxit.h header file*
  
  /** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ***/ 
  /*COMMON STRUCTURES*/ 
  /** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ***/ 
  #define ARCCSXIT_MAX_SRVR_MESSAGE_SIZE 1024 
  
  #if defined(AIX) || defined(HPUX) || defined(OS390) || defined(CICS) 
   #define ARCCSXIT_PATH_MAX 1023 
  #elif defined(LINUX) 
   #define ARCCSXIT_PATH_MAX 4096 
  #elif defined(SUNOS) || defined(__OS400__) 
   #define ARCCSXIT_PATH_MAX 1024 
  #elif defined(WIN32) 
   #define ARCCSXIT_PATH_MAX 260 
  #endif 