2693721 - GW: Maximum number of requests per CPI-C connection reached

SystemLog (transaction SM21) shows entry:

  S0B  Maximum number <nr> of requests per CPI-C connection reached

Checking Gateway trace file (dev_rd), it shows:

*****************************************************************************
*  LOCATION    SAP-Gateway on host <hostname> / sapgw$$
*  ERROR       can't get memory in function GwBufInsert(max request) ( <nr>
*              bytes )
*
*  TIME        <timestamp>
*  RELEASE    
*  COMPONENT   SAP-Gateway
*  VERSION    
*  RC          222
*****************************************************************************

Dumps (transaction ST22) may also be triggered for RFC communications on both sides of the connection, the systems where the source gateway and target gateway run:

CALL_FUNCTION_SEND_ERROR 

Short Text
    "can't get memory in function GwBufInsert(max request) ( <nr> bytes )" (I/O
     error)

What happened?
    CPIC-CALL: 'ThCMSEND', communication rc: CM_PRODUCT_SPECIFIC_ERROR (cmRc=20),
     taskhandler rc: MEM_OVERFLOW (thRc=245)#Insufficient memory in gateway; log
     on again later

    An error occurred while making a Remote Function Call.

    State of connection.. CODE=CM_PRODUCT_SPECIFIC_ERROR CM_SEND_RECEIVED
     CM_COMPLETE_DATA_RECEIVED  SAPCODE=245  CONV=<nr>

     Location.......... SAP-Gateway on host <hostname of the affected gateway> / <service>

PARAMETER_CONVERSION_ERROR

What happened?
    During a remote function call, an error occurred while converting
    a complex parameter.

Error analysis
    An error occurred during the conversion of a complex parameter.
    Last error logged in SAP kernel

    Component............ SAP-Gateway
    Location.......... SAP-Gateway on host <hostname of the affected gateway> / <service>
    Version.............. 2
    Error code............ 222
    Error text............ can't get memory in function GwBufInsert(max request) 

SAP NetWeaver system

Maximum number of requests per CPI-C connection reached, requests per CPI-C connection
GwBufInsert, max request, 222, CANT_GET_MEMORY, can't get memory in function GwBufInsert(max request), gw/req_stack_size , KBA , BC-CST-GW , Gateway/CPIC , Problem